I know there are a stack of threads about this but there's a few different symptoms/causes and I just wanted to double check the details of mine before I waste money/time. Hopefully this is a quick one either way i.e. tell me to close off the thread and read the existing info or crack on you may be into something.

So I get the usual intermittent starting. Turn the key, click, nothing happens. I went through and checked all connections, battery is good etc. If I rock the van in gear then turn the key at rest, it will fire up straight away without fail and with the installation of a new rotor arm and dizzy cap starts strong.
I'm thinking because this rocking effectively frees the starter motor this is more likely to be an issue with the bush rather than solenoid or brushes........or am I being hopeful (and mechanically hopeless) for a cheap fix?
Thanks