My E34 manual isn't handy, but my E30 manual says if the sunroof creaks when used during hot weather, dirt or grease buildup could be the cause; it says to clean the slide rails with a grease-free solvent and anything else that is in contact with the plastic shoes of the sunroof. If the E34 is similar to an E30 and has plastic shoes/slide rails, might be worth checking those if your issue might be related to that. You may need to remove the the sunroof panel to gain access (which is not the sunroof itself, but the headliner trim piece that covers the sunroof).
There is a detailed description with pictures of how to clean and lube an E34 Touring sunroof over on Bimmerforums in the DIY section of the E34 subforum. The disassembly will not be the same but it should still be helpful to read it before attempting to do yours. If you have a touring, then this is the best source of info you can find. I don't have the link but if you search, you will find it.
Does any one have any experiance with converting a "79 633 Csi electric operation sun roof to manual ? or later model electric?
Such a specialized project, I'd be surprised if we have anyone here with much advice. I know on my '87 E30, I think the sunroof motor can take a hex key/socket and be turned manually, as a backup in case of motor failure. I think it has a lot of resistance though, against the motor, so if your motor was similar, that would be a very ersatz solution, and likely not particularly practical or workable. I'd say hit up the folks at myE28.com and that at least gets you into the ballpark with a larger number of folks with cars closer to and of more similar vintage with yours, and a better chance that somebody's had a similar issue.
