Vigier Guitars

My 15 year old Expert needs a new pot. Every time I am standing and playing and push it down a little (towards the floor) it cuts out. The shaft is wobbly.
 
What is the factory standard pot and value, please? Or if not, what is the best brand to replace with? Dimarzio?
 
Thanks!

Dimarzio, Switchcraft or any good quality pot should be fine. We now use 1meg pots, but did use 500k before we changed a couple of years ago.

Thanks Ben, I really appreciate the expert reply. ;)
 
Will look for one now!