Unlike some, I have not had great luck with PB Blaster. As a mechanic sometimes serious rust frozen parts work with just some thing like that. Sometimes you need penetrating oil, heat (like from a propane torche), shock (like from a 4# hammer), more oil, and a cheater bar on the wrench. sometimes you get them apart and some times you have to destroy the cheaper part.

However, I would like to point out that in my molasses derusting test, I got a brake adjuster apart after soaking for a couple of days. I had soaked one in PB Blaster for a year to no effect. So if they are important parts I would give the molasses a try.

Aside: It has been a long long time since I worked on one, but don't the American one piece cranks have right hand threads on both pedals?