'91 xj600 starter problem

[drago]

Hello!
in last times i more and more frequently encounter following problem, when try start my bike - i hear "click" and nothing more. no spinning, no rotate engine, control panel lights shine. second, third try at that - exactly the same result, only on click when i push "starter" button.
i found workaround - put bike in second or third gear or so, and rotate engine throught rear wheel - to 20 - 30 - 50 degrees. after that ( when i again put gearbox in neutral) starter works ok, as it suppose to be - turn around engine.
what is ideas, about problem? i think, from that describes, it is not accumulator, and not wires, because engine \ gearbox rotation not to have any impression on that.
also, as i understand, when starter is not under current, this is disengaged from engine \ transmission, as so, looks like it is not starter engine itself also?
what is mechanism throught who starter engages engine? it can be stuck for whatever reason?