Tearing my hair out over the LH door latch on the Spider.
- At first it wouldn't open with the inside handle. Exterior push-button still worked fine.
- Remove door card and adjusted the pull cable. Suddenly the door would no longer latch - try to close it and pops straight open.
- Slackened the pull cable, prodded all the apropriate levers on the latch - still wouldn't latch.
- Removed inner card (mounts inside handle), door glass, winder mechanism, door frame. Latch still not working.
- Remove latch. Latch is now working.
- Replace latch - still working.
- Replace door frame, winder, glass - latch still working.
- Replace inner card and connect cable - latch still working.
- Adjust cable - latch not working.
- Slacken pull cable, prodded all the apropriate levers on the latch - still wouldn't latch.

Several hours work doing all the above - back where I started. Any suggestions?

Nasty door lock/release arrangement on the Libra, if they are all the same as mine.

My Libra passenger door button often sticks despite numerous dismantling and reassembly sessions, a problem I think is down to the feeble return spring arrangement for the button.

Your problem sounds as though its actually in the latch mechanism itself rather than the release arrangement. I've had trouble with these latches in the past on previous kit car. One thing it doesn't like is thick/oil/grease - in cold weather it tends to make it stick so it doesn't "over-centre" as it should.
Probably something you've already tried but have a go at flushing it out with something thin like WD40.

Thanks oldshep. I noticed the door button issue and modified the mechanism while I had it apart. The problem is that the button has a flat face pusing on the hinged plate inside the door. This causes the button to tilt as it travels in. Ideally the button would have a raised hemisphere in the centre pushing on the plate - this would keep the contact point and the force closer to the axis of the button. I jury rigged a plastic part to push/screw into the back of the button. It engages with a hole in the plate which is not ideal - it would be better if the plate was flat. Anyway - it seemed to work a lot better.

I will try some WD40.

I've had problems with the rod from the key lock popping off the mechanism making it impossible to lock the door but I've never had problems with the latch or the button on mine. A previous owner had replaced the black outer handle with an aluminium one that looks like it was machined from solid billet and then polished. I'd not realised this wasn't standard until looking at the row of cars at a previous Stoneleigh which all had the black ones. I'd thought that it had been done for cosmetic reasons but reading this maybe it was to fix these issues. I was wondering about taking it apart to compare with the standard but as it is working I think I'll leave it alone!

Some developments. Liberally flushed in-situ using WD40. Fiddled around with all the levers and buttons and it started working again. Here's the sequence:

1. Door will not latch - effectively its behaving as it would if you held the inside handle in the "open" position. Try to close it and it just bounces open.
2. Hold the inside handle in the "open" position and push the lock button down to the "lock" position.
3. Release the inside handle.
4. Lift the lock button up to the "unlock" position. The inside handle mechanism clicks and the door starts working again.
5. You can close the door as many times as you like and it will latch every time - provided you open it with the exterior button.
6. If you open it using the inside handle it may work once or twice but reverts to the "will not latch" fault state in step 1 above.

I am hoping someone has had one of these mechanisms apart and knows exactly what is going on and can suggest an easy fix. I can't buy one of these in Australia and even from the UK they all seem to be used. (Used may be OK - it sounds like no one on this forum has had any problems with this part.)

Meanwhile I am going to try lubing it some more.

EDIT. Just discovered that an alternative fix (eliminates steps 2, 3 and 4) is to slam the door a bit harder a few times. Something comes free and starts working again.

Rimmer bros at Lincoln web site show new ones in stock at £102 inc vat.would be good if they are same on other models to have more chance of a good condition used one maybe maestro or montego could be same headlamp switches were the same on some models but had different part numbers on box but parts in box had same manufacture numbers on

102 pounds - ouch!

Update!!!!
Discovered that the problem was probably always there and I inadvertently activated it in step 2 above ("Adjusted the pull cable"). If I adjust the pull cable so that the handle can unlatch the door plus a tiny bit of extra travel, the problem disappears. It only occurs if you apply maximum travel to the unlatch lever. Happy for now but would like to have all that wasted time back!