I've had plenty of problems with those dang sprag clutches. I found that three problems dominate: worn bearings, damaged inner surface, and loose roller housings. The unit takes a massive shock every time it engages, the housing bolts need to be torqued tight: I clean the bolt threads and heads, threaded holes, and housing holes with acetone then put a dab of antseize on the housing countersinks and a dab of red loctite on the bolt threads - then use a hammer and hand impact screwdriver to really tighten the bolts. The antiseize lets the flathead taper slip freely while tightening, the loctite stops it shaking loose.
The inner drive hub bearings should not allow much radial movement at all, its outer surface should be competely smooth. If the hub can move around or the surface is bad, the rollers can slip and chatter: that's what really ruins the clutch. The caps and springs can escape completely even though it seems there's no gap they can possibly fit out through, or even past the rollers. The housing can crack. The bolts can work loose or break off.
If the clutch is slipping and chattering it may be too late to save but if you can fix it just by tightening the bolts or replacing the roller bearing that's cheaper than getting a complete replacement.