Knowledge base · Technical note
Fixing a roll-up door that will not stay latched
A roll-up door that will not stay shut is usually not a lock failure. Working through four checks in order stops you replacing the wrong part.
Check 1 — does the lock tongue move freely?
Operate the latch by hand with the door open. The tongue should travel its full stroke and return cleanly. A tongue that sticks, or returns slowly, is a lock problem — often a spring or a build-up of dirt rather than a worn mechanism.
Check 2 — is the hasp still aligned?
With the door closed, look at where the latch enters the hasp or receiver. A door that has been struck, or a building that has settled, moves the two apart. If the tongue is entering at an angle or only partly, the hasp has moved — no lock will fix that.
Check 3 — is the door track true?
Run the door up and down and watch the track. A bent track or a worn roller makes the door sit fractionally off-centre at the bottom, which is enough to misalign the latch. This is the most common cause of a door that latches when pushed and not when left alone.
Check 4 — have the mounting holes moved?
If the latch or hasp hardware has been replaced before with a non-matching part, the mounting holes may not sit where the original did. Compare the hole pattern against the door manufacturer's drawing, or against a unit elsewhere on site that still works.
What this means for the replacement order
The order depends on which check failed:
| Check that failed | Part to order |
|---|---|
| 1 — tongue | Latch assembly or return spring |
| 2 — hasp alignment | Hasp / receiver, plus door adjustment |
| 3 — track | Rollers or track, not lock hardware |
| 4 — mounting holes | Mounting plate or a drawing-matched latch |
Send us the door type, the mounting dimensions, or a photo of the existing part, and we will match it. Where the original is discontinued, we work from the drawing or reverse-measure a sample you send.
Confirm it on your own doors
Send a door photo, the cylinder size or the mounting dimensions. We confirm fit with a physical sample before you commit to a quantity.
What readers ask next
Establishing the cause before ordering a replacement.
Can you tell from a photo whether the lock or the door is at fault?
Often yes. Send one photo with the door closed showing the hasp, one with it open, and the lock tongue in frame. We will say what the photos show and what still needs measuring.
If the door is at fault, can you still supply the hardware?
Yes, but the door has to be corrected first or the new part fails in the same way. Send the door make and model and we will confirm what the hardware needs from it.
How long does a replacement part take?
Standard parts follow the normal batch lead time, typically around 30 days, which is why spares are worth holding for the doors that fail most often. Send the original order reference and it is matched to that.