Every few weeks or so I take apart all my Baitcasters and give them a good cleaning, sometimes more often if they get to dirty. Then I oil and grease them up and put them back together. I started noticing with some of the reels that cleaning them was not helping the performance of them to much. I found myself back lashing more often and my cast and retrieves just were not a smooth anymore. I would get a reel setup make a few cast and then it would seem as the reel would need readjusting.
The other day I took one of my reels apart, cleaned out all the dirt, old grease and oil I could see or get to. I put it in my sonic cleaner for a few cycles and to my surprise there was a lot of dirt , and grease in the bottom the tray the cleaner got out that I could not get to. After the cleaning I set all the parts out on a towel and let air dry for a bit before adding grease and oil. I am not worried about rust because my machine heats the water so hot the parts dry almost as fast as you pull them out.
I used the reel the other day and not one back lash. It was much easier to set up every time I changed a lure and keep its setting. It cast and retrieved very smooth.
It seem that all the small small crap I could not clean out before was building up and making my reel mess up...
Just thought I would share what I learned and maybe that reel you think is wore out just needs a good deep SONIC clean...