The flat spot on the rubber drive wheel seems to be a weakness on ALL machines using that system, not just the Elnas. I think the problem with the Elna is the pulley is apparently hard to access. I've been tempted by the green Elna Supermatics I've seen but haven't pulled the trigger due to that reason.
I'm still buying machines to fill in gaps in capabilities. I still don't have a machine with a free arm and decent metal ones seem to be a bit uncommon.
Rodney