The 6 Speeds On My Oster 2534 Do Not Work; Only The Burst Of Power Works.

In order to facilitate a quick understanding of my problem, I have capitalized what's REALLY IMPORTANT!I purchased the Oster 2534 in the early 2000s while we were building our camp (because it was on sale and just what I wanted). It was a couple years before I got to use it and I immediately realized ONLY THE BURST OF POWER WORKS! I figured it was too late to return it or get satisfaction from a warranty. I don't use it often at camp so I've managed with that one (fast) speed. However, I recently had reason to wish I had a lower speed when I was trying to mix in a cake mix and it began getting blown out of the bowl using power burst! I DECIDED TO SEE IF I MIGHT BE ABLE TO GET A PART AND FIX IT. Would you please advise me on:WHAT PART(S) I NEEDHOW TO GET THE PARTS HOW MUCH THE PARTS COST WHERE I CAN FIND INSTRUCTIONS ON GETTING INSIDE THE MIXER HOW TO MAKE THE REPAIR? Thank you for whatever assistance you can give me.PATRICIA REICHHART