0403jacqui

Hello -can anyone help me? I have purchased a 1998 low mileage slk. Roof was working fine. Then over the last two days when we have had hot weather the roof has been sticking down. Basically after I have had roof down for a few hrs and it will not come back up properly. The windows go down and the boot flap opens but the roof wont budge out of the boot area. I can hear it trying but it wont do it. I have left it over night and tried again in morning and it works first time! There are some older posts on here with same problem about faulty microswitches but the links don't work. Can anyone tell me what it might be and where the microswitches are located? Thanks.