Hi DC

​My first guess for this problem would be sagging suspension. If you look at the bottom of your unit, you will see 4 screws just in front of the front feet and just behind the back feet. Now look just above where these screws are and you'll see 4 rubber spacers that have probably flattened allowing the mechanism to sink down in the body so the carriage contacts the body stopping its travel. If these have flattened out, they will require replacing.

I believe I read somewhere on this forum that 5/8" tap or faucet washers make acceptable replacements for these rubber spacers. I have cut washers from 5/16" thick rubber conveyer belt material as replacements for these spacers. Take a look at your machine and see if we're on the right track. Other members may have ideas that I haven't thought of, listen to what they say, learn from their experience and hopefully you'll be up and typing again before too long. All the best,

Sky