Paragon B-555 500 watt light replacement

[JEBrubaker]

I have a 30'x12' concrete inground pool built in the early 1980's. Purchased the property 7-8 years ago. Light has never worked. Drawing the water down this year and painting. So I had an electrician come out. Found out none of the wiring was up to code, and not on proper circuits, and not protected with GFCI's. So just completed re-work to address electrical deficiencies. Pulled pool light. Brand is Paragon B-555 500 watt light. Actual screw-in bulbs in a sealed housing. We can get the light to work if we wire direct (not through GFCI). But when we have it through the GFCI, the light kicks the breaker the second you flip the switch on. Electrician has checked and rechecked everything. His only final comment is that there most likely is a short somewhere in the fixture or the wiring harness up to the junction box above the water level. His suggestion is to order a replacement sealed light fixture and wiring harness assembly. I have searched Paragon online. Not seeing any clear direction for replacement parts. Looks like company may have been sold? Can any help point in the right direction and/or offer any other suggestions for replacement?

Thanks!