There's probably a manufacturer's name - Shakespeare, Digital Antenna, etc - and a model number on the antenna. Go to the manufacturer's website and see what that model antenna is for.
There are only 2 companies I know that make keel protectors, and both offer a lifetime warrenty. I would confirm which of the 2 you have and call their customer service team.
I'm a former black belt TaeKwonDO. I loved it until I came to the realization that there is alway someone meaner, badder, bigger and more willing to fight or just do damage. That's when I quit. But several years after resigning from karate i stumbled on Aikido. It it the best martial art...
I would never, ever, EVER recommend these guys but look how they had to launch.
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I had the same problem and found the culprit the same way you did. I found that the belt was slipping on one of the idler pulleys. I used fine sandpaper and sanded the area of the pully that the belt was riding on and the squealing has yet to return.