When the new rod kits for Maico's got scarce I discovered that the original crank roller bearings were 3mm which is roughly .120 Dia. So what I did, was find 1/8" american size rollers the same width, which were .125 Dia. open the cage up with a jewelers file so they fit. and then take the rod, a good pin, the bearings and cage to a good automotive machine shop and have the rod machined to just clear the new rollers and pin. Got me out of a bind a couple of times. Might be worth looking into.