Most likely you need to replace the AC line filter caps. They are there to prevent RF from exiting the transmitter via the AC line. Be sure and use X1/Y2 rated caps.
There are other possibilties - shorted AC line wire to the chassis, power transformer winding shorted to the chassis, etc., but the line capacitors would be my first suspect. Should be very easy to find with a VOM.
This guy is in Canada and sells 'em
http://www.justradios.com/X1Y2capacitors.html