Hello,
Looking for confirmation or new ideas..

Delta 12" miter saw has served me well for 20 years with basically zero maintenance ever.

Recently, swapped in a new blade (same brand/style as the blade that it replaced) and began noticing that during braking there was a "whirring" sound that was new, and the braking happened more slowly than before. Blade used to spin to a stop in (say) 2-3 seconds, and this was now (approx) 5-6 seconds. Enough to notice, but not cuts were good so I didn't give it much thought.

Flash forward a few weeks and several hundred cuts and the blade got stuck in piece of 3/4" pine. That was surprising. The arbor nut had loosened. Weird.

I figured perhaps I hadn't tightened it well enough, so I went to tighten it. The arbor nut was hot to touch. Snugged very tight, I made a few more cuts and was able to complete the task but can noticeably see vibration and the whirring sound is still present. Luckily that task was a carpentry task and the cut was sufficient, but time to fix this.

My research tells me I ought to:
1. Ensure arbor shaft and washers are all nice and clean, and try another know-successful blade (e.g. the blade I just recently used)... perhaps the replacement blade is just defective and a bit too thin or is warped, or some dirt/grime is the culprit.

2. If easy fix above doesn't resolve, replacing the arbor bearing seems the next logical step. Appears from quick research that doing so is far easier on a miter saw than my previous experience on cabinet saw.

3. Some have mentioned that brushes could be part of issue in some cases, but I think arbor bearing seems more likely for these symptoms.

What say you SMC gurus?