I just installed a new 5G type gearbox on a tapershaft 142. The clutch that came with the gearbox has a notch for a key and the tapershaft has no slot machined into it. I understand that this setup is a "compression fit" only being held in there by a bolt and washer. Bottom line is that the clutch is slipping badly on the first road test and I'm unsure wheather it's the clutch or that the clutch is just slipping on the shaft. Any ideas?