Recently removed the passenger headlight motor as it had stopped working.
Yesterday I took the car for a service and switched the headlights on, however the drivers headlight now only pops up on it's own. To lower it I have to do it manually.

Any idea why this is happening?

 

Are you able to provide power and ground to the motors to 'jump' them? If so, try it and see if they operate. If you don't have movement still, or turning motor type of noise, you probably have a bad motor. If, when you apply the power and ground and the motor operates, you most likely have a bad headlight motor relay.

It is sometimes possible to reflow the solders in this guy (after taking the black outer plastic shell apart to access the relay itself), but sometimes the relay is simply dead.

Doing a google search for 'third gen headlight module' should get you going in the right direction I would think.

Hope this helps.

 

a lot of times you can tell it is a bad headlight module (the module on the face of the firewall) by pressing the connector plugging into the module in some different directions and seeing that the motor now cycles... if it does it is a loose connector to board inside the module and as noted above taking it apart and resoldering can fix this... on the ones i have done the connector on the driver side was the loose one

 

Fro. Your first post it sounds like you have the on we motor removed right now. You should plug the other one back in and see what happens. I know that when o redid mine that they acted weird when the bulbs weren't installed or just one motor hooked up.