I'm the proud? owner of an ancient looking 0-280 volt 28amp 
Powerstat.  It seems to work OK, but I've only tested it on a 120 volt 
line and with a light load.  On inspection, I see that the wiper 
brushes are worn and in need of replacement.  Does anyone have a 
source for new brushes or the address of Superior Electric?

	Can this transformer be operated at higher current levels than its 28 
amp design spec?  It has a 30 amp fuse, so this will obviously need to 
go higher.  I would like to operate it intermittantly at 40-45 amps.  
Would forced air cooling help?