Hi, I’m assuming you have the engine running when operating the roof? If the answer is no you may have a weak battery, if the answer is yes you could have a partially drowned roof motor, have you checked the drains are clear since you’ve owned it? It could still have been flooded in the previous owners care mind you :?
Rob
Where are you based, there are forum members who can bring dead motors back to life and also move it to the boot. It stops the motor sitting in a pool of water.