Gainsborough Trilock door latch won't stay closed

If your Gainsborough Trilock door won't stay closed it could be caused by a broken spring for the latch/deadbolt.

If the latch/deadbolt is not springing out as far as it needs to then you will likely need to replace the spring.

You might be able to get it working again by stretching part of the broken spring but that probably won't last long.

You can buy new springs in Australia for about $20 to $30 posted but if that seems excessive for a tiny little spring then you can find a generic spring from somewhere else cheaper.

For example, I bought a packet of 20 springs for less than A$4 from Aliexpress.

The size of the spring that worked for me is 3mm outer diameter, 30mm long and 0.5mm wire diameter. It's a pretty tight fit so you probably wouldn't want to stray from those dimensions. Even slightly thicker wire might not fit.

There are probably better guides on how to replace this part on YouTube but the basic instructions are as follows.

1. Unscrew the four phillips head screws that hold the inside to the outside.
2. Be careful as you separate the inside and outside parts. There is a part that slots into the outside part from the inside. This part can go on four different ways and affects how the lock works. You can work out which way is correct but it is easier if you take note of how it was installed.
3. Once you have the inside and outside parts off you can remove the two screws from the cylinder - one on the inside and one on the outside - that secure the bit that sticks into the door frame.
4. Then you can can unscrew the two screws on the side of the door and attempt to pull that outwards. You need to rotate the cylinder or rock it back and forward until the latch/deadbolt slides out.
5. Then you can pull the latch assembly apart and find the pushrod and spring.
6. Fit your new spring on the pushrod and put the latch assembly back together. Then slide that back in the door, again rotating the other part until it can push into place and screw it in in.
7. Then put the two screws back into the cylinder.
8. Screw the four spacers into the outside door part and then hen put the outside part in and align that inside part with it, then attach the inside part and check the lock works how you want it to.
9. Then install the four screws and you are done.

Hopefully that works for you.

One extra tip is do not test the door without the plate installed that attaches to the latch assembly on the side of the door. This can cause the latch/deadbolt to get stuck in the door frame and you may find yourself locked inside or outside and unable to open the door, like happened to me.