I'm assuming you are talking about the starter solenoid here.
So, based on that, why not source a new one you can get at a moments notice and then try to clean and reassemble the old part.
If it all goes South, let the rest of us know then go collect the new bit, you've lost nothing and gained the experience.
But so far as I remember these starters are a real sod to get out, so I'd recomend fitting a new solenoid, refitting the starter and then playing with the old bit to make an emergency spare, or they may be so cheap from Lighthouse that it's just not even worth getting your hands dirty!
