What symptoms did you get and for how long before you lost drive GLLOQ? How many miles had the Centa drive done before failing? Does your gearbox bellhousing have the hole for lubricating the original compensator War Bird? I cannot see any other easy way of inspecting inside. Unfortunately my car doesn't even have the lubrication hole but ignorance may be bliss.

This doesn't surprise me as the loads taken in the M3W installation are not constant or in one direction. The Centa drive will have a hard life. As mentioned, some ventilation may help extend the life of the rubber rollers but that would be a big job and may introduce contamination that would increase the wear rate.