My rear passenger one played up last week. Was making a horrible noise and wouldn’t lock or unlock.
I took the little rubber gasket off and sprayed copious amounts of wd40 at it, whilst unlocking and locking the car and working the red paddle for the mechanism at the same time.
Eventually it started working again. No idea if this was just luck or whether what I did actually had an impact, but it’s been fine since (touch wood).