Hi Steffen,
I bought an HEQ5 earlier this year and didn't like the gear train 'graunching' noises. Way too loud to be neighbourly at 1am.
I've been working on a standard 9:47 ratio belt mod for the HEQ5 to allow the Synscan controller to be still used and to improve the tracking too.
The pinion gear on the motor is loctited in position and can be tricky to get off the motor shaft.
I made a small extractor which made the job worry free !
I posted a thread on Stargazers Lounge
http://stargazerslounge.com/topic/18...-947-belt-mod/ which shows the steps I made to get it all working.
The 9 tooth pulley was the tricky one ! I didn't find any supplier who stocked them.
I ended up machining them myself from bar stock in one operation which meant concentricity and true running was spot on.
If using stock pulleys, boring them out to size has to be done very carefully to ensure concentricity which is tricky to do if they have flanges.
Dave.