I've had the Problem Solver (book and tape) for years. I think you can only get it from ipd (just the book) and at a sale price they're either trying to promote it or get rid of it. It's basically a collection of 168 one or two page notes and diagrams of common problems and tips from Robert Gerhardt. Initially I found it fairly educational, especially on the early D-Jet and K-Jet systems, but I rarely use it now as the coverage wanes after the mid-80's models. Some of the information found there is not easily found elsewhere, mostly because of the diagrams.

Just MHO though.