I had a machine that was locked up. By process of elimination, I figured out which piece it was. I removed that piece and soaked it in PB Blaster...bit by bit, I was able to finally move and then remove the bushings that were causing the trouble. I was warned it would remove varnish, so I was careful with it...I sprayed some in a narrow little jar and just let it soak.
I found both the PB Blaster and Tri-flo at Fleet Farm to my surprise. Very inexpensive.