Sigh... You should talk to a Pentair expert, but it looks like the
updated version of this light is 602188, and I'm
seeing prices over $1000. You might find a pool supply place with old stock.
A couple of notes:
1) Your light is actually 120 vac, not 12. There's no external transformer for this version (only inside the light itself). Again you should listen to experts, but failed light might be a leaky light. 120 volts in contact with water is never good. If it were my pool, I'd not turn them on again until the faulty light is physically disconnected at the junction box.
2) Price of these lights can vary pretty amazingly with length of wire. If your installation can use one of the shorter lengths, it will save some $$$.