I bought a cheap elliptical / exercise bicycle. I didn't know if it would get much use. And if it did, then I could justify a more expensive unit. It quickly developed a clunk in the pedals. I disassembled the covers to inspect the drive, expecting to find the bearings were failing. The belt had a fixed tensioner, not spring loaded - the pedaling resistance was adjusted by a drum brake unit. I don't know how they assembled the tensioner - the belt was ridiculously tight. I had to struggle to unbolt and remove the tensioner - it was at the end of the adjustment for 'looseness'. After several minutes of pondering I re-routed the belt and re-installed the tensioner. The belt is now snug vs. piano string tight. And the clunk is gone.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.