for removing the motors I used a Phillips head bit from a screwdriver, with a small spanner (6-7mm?) to turn it. This allows you to stay quite close in, as the subframe tends to get in the way.
There are two screws, top left and bottom right as you look in (upside down, from the front, if you understand?!)
Getting the screws out is no easy job, they're long (maybe 40mm?) and have a good bit of thread on them. So keep at it if you think it's turning, don't give up half-way.
If you get the screws out, removing the motor is awkward enough. you need to push down on the stalk that pushes the lamps in and out. This will (hopefully) pop it out of the groove in the lamp housing that it sits in. Then it pulls back easily enough.
Remove the connector.
Open the back of the motor by lifting all the clips around the back lid.
The board with the controller comes out by pushing the pcb from the front on both sides while also pushing down a little plastic spring-clip that holds it in. Remember to unclip the actuator gear (white plastic) from the variable resistor, or it won't pop out easily).
With the board out, I've just used some wd40 and wadding to clean the corrosion off. Chances are if it's corroded it's bust though, and that means off to the breakers with you.
Alternatively it should be possible to replace the units without controller, and manually adjust the tilt using the actuator inside. I'm going to try doing that this weekend.
A lot of the descriptions above probably won't make sense until you're actually doing the job (and even then
), but I'll try to get some pictures this weekend if it's any use?