Steve, I can't imagine that everyone is having similar problems. I have changed most idler pulleys when they start to make noise or I can feel rough bearings, but I'd expect a lot more complaints from folks if everyone had similar issues. We just cut grass in a dry and dusty environment. Since the idlers are above the deck, you wouldn't think they would get sand blasted like the bottom surface and blades, yet, I've sure had my share of failures. The blade tension is completely a function of the large idler and the tension of its spring. Engagement of the electric PTO is ON or OFF, there's no feathering it and we start it at mid-rpm range as the operator manual suggests.
Does your deck have two small idlers and one large idler? Electric PTO? Is the first idler off the electric clutch a small one that has a rigid mount with no spring for shock absorbtion? Believe me, I'm looking for reasons for our problems, but we are doing nothing out of the ordinary for any riding mower we have ever owned. As I've said before, thank goodness parts are cheap and easy to replace. I put a new set of blades on every year and sharpen them once before they have to be tossed because they are eroded away. I'll replace parts as they fail as long as I can get them from JD. Parts support has been terrific. The dealer is very helpful.