I have a 51 focus that has key only central locking. The problem i have is with the front passenger door. I recently swoped the whole lock unit as i was having problems with central locking, everything started working fine until now when the drivers door lock only occasionally works the central locking (guess i need to replace this unit too).
When the locks are operated inside with the switch everything locks fine, but if you try to use the switch on the passenger side to unlock it is really stiff and wont move. If you use the drivers side it then unlocks all doors (if it decides to work at all). Anyone got any ideas?

The 2 problems are:
1 - drivers side occasionally working central locking
2 - Passenger interior locking switch cant be pushed into unlock position