Swendl

After two years of faithful used, it appears the heater on my tub is dead. The tub electronics (bubbles, circ pump) work fine. However, when the heater is engaged, the GFCI trips within about 10 seconds. Having disassembled the unit, I have found the heater part and would be interested in replacing it, but I can't find any source of supply online. The closest I can find is vendors wanting to sell the entire pump unit. Any suggestions would be welcome, either on how to repair or where to buy.