What lubricant should I use on my uPVC door lock?

For the cylinder, use a dry PTFE spray or graphite powder. Not WD-40 and not any oil-based product, they attract grit and dry out fast. For the multipoint mechanism, the hooks and the keeps, a light machine oil like 3-IN-ONE is fine. Apply it sparingly, work the door through a few lock and unlock cycles, then wipe off any excess from the face of the door.

My key turns stiffly in the lock but the door isn't misaligned. What's wrong?

Nine times out of ten it's a dry or dirty cylinder. Try a PTFE spray into the keyway and work the key in and out about fifteen times. If it's still stiff after that, the cylinder is wearing out internally. Budget £40 to £80 fitted for a replacement TS007 3-star cylinder such as an Avocet ABS or Ultion. Don't leave it over winter. Worn cylinders seize in the cold.

How do I know if my multipoint lock gearbox is failing?

Classic signs are the handle feeling heavier than usual when lifting to lock, a grinding or clicking sensation mid-throw, or the door not pulling fully into the frame when you lock it. If the cylinder is fine but the mechanism is the problem, the gearbox needs replacing. Depending on the brand, GU, Fuhr, Maco, Roto or Winkhaus, a replacement gearbox and fitting typically runs £90 to £160. Leave it and it'll fail completely, usually at the worst possible moment.

My back door has always been a bit stiff to lock. Is that normal?

No. It means the door is out of alignment, the mechanism is worn, or the locking points aren't meeting the keeps properly. 'Always been like that' is how lockouts happen. Check the hinges first. If they're tight and the door still rubs or fights you, the frame may have shifted or the keeps need adjusting. It's worth getting someone to look at it before the wood swells over winter and a stiff door becomes an impossible one.

How often should door locks be serviced?

Once a year is a sensible minimum for any door in daily use. Autumn is the right time because you're preparing for the worst weather. Front doors on busy family homes, or any door on a rented property, probably want a look every six months. A landlord with houses in Harworth or Rossington on an AST should be doing this between tenancies as a minimum anyway, both for the tenant's security and to avoid an expensive emergency call-out mid-winter.

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Steve Marsh, Lead locksmith·19 June 2026·6 min read·

lock-maintenanceautumn-securityhome-securityuPVC-doorsBawtry

Autumn Lock Maintenance Check | Ten Minutes Now Saves a Lockout in January

A practical field guide from Steve Marsh at Rapid Response Bawtry. Lubrication, weatherseals, stiff keys, loose hinges. Do this before winter hits.

I had a call-out to Austerfield last February. Bloke couldn't get his front door open at half six in the morning. Work van on the drive, coat on, keys in hand. The lock hadn't been touched since the house was built. The gearbox had seized solid overnight when the temperature dropped. Twenty-minute job to get him in, but his morning was wrecked.

That job was entirely preventable. Ten minutes in October would have done it.

Autumn's the right time for this. Before the first proper frost, before the timber swells or the multipoint mechanism decides it's had enough. Here's what to actually check.

Lubrication. Get It Right or Don't Bother

The number-one mistake I see is people squirting WD-40 into a lock cylinder. Don't. WD-40 is a water displacer, not a lubricant. It strips out the grease that's already in there and leaves the pins dry within weeks.

What you want:

Cylinder: A dry PTFE or graphite spray. Squirt it into the keyway, insert your key, work it in and out a dozen times. That's it.
Multipoint mechanism and locking points: A light machine oil or a dedicated lock lubricant like 3-IN-ONE. On a uPVC door, run it down the edge of the door where the hooks and deadbolts engage the keep. Open, lock, unlock, open again. You want it working through the mechanism.
Hinge pivots: A smear of grease or petroleum jelly on the exposed parts of each hinge. Not much. Just enough to stop metal grinding on metal through January and February.

Do not over-apply anything. Excess lubricant collects dirt, and a gritty cylinder is worse than a dry one.

The Stiff-Key Warning Sign

If your key requires noticeably more effort than it did six months ago, pay attention to that. A cylinder that's stiffening up is one that's either drying out, picking up debris, or, more likely on an older door in DN10, starting to wear out.

Try the lubrication above first. If it's still stiff after that, the cylinder wants changing before winter. A worn Yale or ERA own-brand cylinder that's been on a Bawtry semi since 2008 is not something worth nursing. A decent TS007 3-star replacement, an Avocet ABS or an Ultion, costs £40 to £80 fitted. A lockout call-out in January costs more and is considerably less fun.

Also check: does the key go in smoothly but turn hard? That points to the mechanism, not the cylinder. The multipoint gearbox on a tired GU or Fuhr lock has a finite number of cycles in it, and cold weather is what finishes them off.

Weatherseal Condition

Run your hand around the frame of your front and back door. The seal should compress slightly and spring back. If it's brittle, cracked, or coming away from the frame in sections, air's getting through and so is moisture.

That matters for locks because moisture ingress around the frame speeds up corrosion on the keeps and the exposed parts of the locking points. On a timber door in Misson or Blyth that's not been painted recently, it also means the door itself will swell more dramatically when it gets wet. A door that's already rubbing in October will be a genuine fight by December.

Replacement draught seal strip is a few pounds from any hardware shop. Push it into the groove, trim it at the corners, done. If the seal is bonded on and has given up, that's a slightly bigger job but still straightforward.

Hinge Check

Grab your door near the handle side and push and pull gently. Any rock or movement means the hinges need tightening. On a uPVC door, the hinge screws are usually visible once you open the door fully. On a composite, they may be concealed under a cover.

Loose hinges put the door out of alignment. An out-of-alignment door doesn't engage its locking points properly. And a multipoint that's already working harder than it should to pull the door into the keep is exactly what fails on a cold morning. Tighten each screw. If a screw turns but won't bite, the thread's gone and the hinge needs replacing or the hole needs filling and re-drilling.

While you're at it, check the keeps on the frame. The screws on these take a beating every time the door's locked. A wobbly keep defeats the purpose of the lock entirely.

One Last Check

Lock and unlock every door in the house. Back door, garage door if it's integral, any French doors or patio doors. You're listening for grinding, feeling for stiffness, and noting anything that's changed since spring. Problems that are minor now tend to get worse, fast, once the temperature drops.

A lot of the work I do across Bawtry, Harworth, Rossington and Tickhill in winter is jobs that were brewing all autumn. The check above takes ten minutes. Most of it costs nothing.

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