The whole thing of O'scopes is manifold. Having a scope adaquate for tha task. Generally an operational Tektronix 465B, 475 or the newer equiventls are an excellent bet. However.. The other is having the right probes, knowing where and how to hook up. With all that accomplished you fire it all up and are faced with a display that doesnt match what you wish(hope) to see. So you twiddle the knobs and its still different. The problem is now interpreting the display and taking the required action IE: adjust scope or adjust equipment at hand or maybe even fix broken equipment. The latter part is far harder as most people have no point of referece to what it all means. That the part of learning to use a O'scope many of the books and site may not even touch. Sometimes if your tweeking a disk the manuals will provide a procedure down to the nth detail and if followed and the drive is otherwise working it's easier. The usual problems is "I made xxx adjustment and I'm to the end and it's still a bit off. What do I do?". There knowledge and experience really helps. If your tweeking a RK05, one suggestion. Find a mentor (EXfield service guy maybe) that has done it before. Even if it's dim memory it maybe very helpful. Allison