You may want to look for a warranty center close to you. Have them look at it. I had 2 of the Porter Cable Saws, the 16" then the 18". Never had that kind on problem, just wore them out. Not sure how it is put together but you may have a bearing that went bad. If it is the 90 days and you have your receipt you may want to take it back for an exchange.
Best of luck
Oh, welcome to village