Hi, just last month got an 05 67k Mk1 VRS. Absolutely enamoured with the car - although have a slight issue. The rear O/S (Drivers side) door is very intermittent with whether it is locking or not. I thought it would be the microswitch however the chrome door pin always reacts when I press the key to either lock or unlock the car - almost as if the motor/actuator is not strong enough to open the door? My gut would tell me if the microswitch was faulty then the silver pin wouldn't be wiggling when I pressed the key - surely if it was microswitch nothing would happen at all when it wasn't working - then operate completely as normal when it does work? I have looked through about a million forums but I can't diagnose what my problem is! Not deliberately trying to necro old problems that have a million solutions already - honest.... 

Had the same with my 2004 octy , same door , eventually just locked and would not open , bought a Door lock Mechanisum from ebay £25 , took door card off and fitted , not a big job , enough info on utube to follow .

My Mk 1 had the same issue on more than one door. In each case I squirted a variety of light lubricants through the small holes in the door edge or took the door card off and sprayed over the lock mechanism. All door locks were still working when I sold the car three or four years later. If you take off the door card you will probably find the outside of the lock looks corroded. The insides are probably the same or lacking lubricant. Anyway, worked for me. I should add that you need to exercise the lock many times before it becomes fully effective.

Ebay chinese pattern locks are perfect. Easy to swap, just make sure the same amount of threads on outside door pull cable are visible after changing as before. 1 thread is enough for it to not work...

And.. have a sheet plastic, sealant and duck tape ready to replace the membrane or youll be joining the leaky mk1 club

Thank you everybody  got a job to do now then - is it a definite having to redo the membrane? Dont fancy having to sort out damp white carpets!!

Yes. You need to seal up the membrane by replacement or, if your careful, high quality tape.