Re: selespeed problem
I trust you've had a read of some of the back posts for selespeed?
The two biggest killers are batteries and fluid level.
First check you have a tip top battery up to the job, needs to be a real meaty one. Im sure someone will advise you the exact figures to look out for if you can't find them in backposts. You can meter it to try and get a gauge for if the one you have is up to the job, or just bite the bullet and buy a new one and try it.
Second, the selespeed fluid level is something to check. Things which could indicate problems are low fluid levels, or if you seem to be topping up quite a lot, or milky/cloudy fluid inside. They can give good hints as to what the problem is.