That link by Rversteeg is good. There’s also a couple of other “how tos” , one of which is mine, which I’m trying to find. It’s title is 940 Headlamp Wipers. Overhaul?? I’ll try to post a link later.
The motors are mounted on the under edge of the headlamp and the fittings are usually badly corroded but it is NOT necessary to remove the motor to service it. Removing the complete headlamp unit gives access to the motor. The motor cover can then be removed without removing the motor from the headlamp.
https://www.volvoforums.org.uk/showt...ipers.Overhaul
Hopefully that’s the link.