Hi
redstar and welcome to the forum!
Roof issues...what roof issues...

Seriously, I presume you have tested the roof on the car you are buying and providing the roof operates without a fault, I wouldn't worry. As long as you only lower the roof when the engine is running and don't interupt the process in any way e.g. switching off the ignition, opening/closing windows or doors e.t.c everything should be fine.
