Pro mouse probs

Hi, I'm having a problem with the pro mouse on my son's iMac. It's a G3 runs os 9.1. Blue coloured.
When it's switched on, the mouse icon on the screen does not move, pick it up and the light flashes for about 10-15 secs then stops, mouse then works for about 5 secs then stops completly.
Can it be fixed or does a new mouse need to be bought, it's a sealed unit, cant get into it.
Customer relations at my local comp shop is appalling, not getting anywhere, so thought i would try here.
My son has learning probs and imac is brilliant for him and he is desperate to get back on.
Can somebody please give advice.
Many thanks.

 

Hi,
The mouse is used on a ordinary desk table, the light flashes all the time now whether it's picked up or not. And mouse icon doesn't work at all on the screen.
thanks for replying.

 

Hi,
I've treid it on every surface poss today, desk is just an ordinary wooden type table, i've even tried it on the wall, light flashes all the time weather it is sitting still or picked up, nothing will work, there is nothing plugged in except key board and mouse, i've tried switching between usb ports on the key board and twiddling for loose connections, no luck, looks like it might be knackered but had to try here for advice, if it has to be replaced is there cheaper alternative rather than paying for a new pro mouse.
thanks for quick replies.

 

Thanks for your help..appreiated.