from being solid to flopping about in the breeze. Any suggestions?
Your cranks are ruined! Once ridden in the “floppy” mode, the square taper in the crank can no longer be secured on the spindle. Get some new cranks and properly tighten them after lubricating the tapers. Proper tightness can be guaranteed only by torque wrench or a skilled mechanic. The second of these is less expensive and you might be able to get a demonstration of what is tight enough. The admonition to not lubricate the tapers of the crank spindle seems to find life only on bicycle cranks, of all the machines I have seen. I have pursued the “dry assembly” instruction by talking to crank manufacturers and discovered that they apparently had warranty claims from customers who split their cranks open. It is easy to prove that cranks cannot split by over-tightening simply by attempting to do so. It is not possible to split a major brand crank this way, the bolt will fail first. Crank failure from “over-tightening” is caused by the re-tightening of previously properly installed cranks.
