Originally Posted by
dwsmartins
It should serve the purpose to prevent losing tension, right? If that’s the case, maybe this is the root of my troubles!
Yes, this could be a problem. I'm not sure if a lock washer is correct for every HT crank as some, if not all, have flat washers. Some of the OEM bolts are model specific and include washers.
EV-FC-M542-2681A.xls (shimano.com) Also make sure you have the axle washer (#5 in the diagram) in place as they can sometimes go missing when the crankset is removed.