I would agree with all the logical explanations and procedures described by the respondents here, except;
with a 500...
Throw all logic, systems, processes and sensibility out the window. They are the most impossible, frustrating little POS to track and balance. After a lifetime of tracking and balancing everything, these things were impossible and I had some really experienced 500 guys working for me. I'll show them how it's done, I thought, after they had fruitlessly spent 3 days farting around with one, including balancing the bare head, changing multiple blades, then changing the entire set out, followed by 2 sets of dampers. Two days later I was no further ahead and we started from scratch yet again. Throw away the logic and record of adjustments and just go for it. We had our best success with a microvibe, but they were never fast. Didn't matter what type of blades or set-up - and some of them were just impossible to do anything with. I have never operated a 500 since then (and I had a bunch of them), and will never, ever operate one again.
Apologies to the original poster who didn't ask for any information on a 500.
