With the weather as warm and muggy as it's been lately, I'm sure the house/shop whatever fans you have, are doing over time. I've had my share of dried out bearings and just plain seized up fans over the years and have found an easy fix with minimal labour. The oil lite bearings gum up and get sticky or seize and then a lot of the fans get pitched out. I've used 3 in 1 oil, regular oil, Marvel Mystery oil, and just about anything else that was slippery but the problem would be back in a few days or a couple of weeks at best. Then one day just for the heck of it, I used chainsaw bar oil....I think I found the answer. I have a small 10 inch fan set up beside the computer for my personal breeze. It suffered a seizure a little over two years ago, cleaned up the shaft with crocus cloth and rolled up a piece of fine emery for the inside of the bearings to clean things up. A couple of drops of bar oil (I use the winter grade, only because that's what I had on hand) and it's been humming along like new. I've started it up during the winter after it had sat for a few months and it took right off. In the past this is when it would usually tighten up or get draggy. I have found it works equally well on most electric motors that sit for awhile before they get used again. Works well on electric drills etc too. Keep cool. Sniper.