I changed my belts myself last month, its actually not as difficult as you would imagin, i used the tutorial on clarks garage (
http://www.clarks-garage.com)
Its relativly simple, if your changing the rollers then the tools come in dead handy, only other advice i would give is if your doing the change while the engine is still in the car then try and do it inside a garage with lights as it can be time consuming, also remove as much as you can to give yourself as much space as possible and take note of which markings on the balance shafts you need to be looking at, when i first did mine i presumed that the markings on the front of the rollers where what i needed to aline to, but it turned out i had to ignore these and look as a tiny triangle in the back plate instead, im sure many a garage not used to 944's would do the same, but this varys depending on what year so read up on clarks first, all the info is there, if its any help i have a rebuild engine out of the car and can take reference photos to help if you wish
