My passenger door lock has now started to make a funny noise when I go to open it.

More and more it also fails to open, and I have to lock and unlock maybe several times to get it to open.

Is it time to replace the lock motor before it goes completely?

Any idea on part numbers, cost and difficulty?

No problem in stripping the door down as I have the bolted on carriers so is quite easy to get to

I've taken a video of it

I got a new one from the dealers was about 120 quid.

unit 18 fitted mine as it was rivited on. but took them under 1hour

Try stripping and cleaning and then lube it with silicon grease. Good chance it's gunged up with dirt