Replacement Bulb question

I have to replace my Spabrite/AquaLight Underwater pool lightbulb and need some assistance. I purchased a replacement 100w 12volt r20 bulb from my local pool store, however it isn’t nearly as bright as our original bulb.

Attached are some pictures that may help

I can easily find the gasket I require 79108600, but having difficulty finding a new bulb

What are my options for replacing the bulb? Can I switch to halogen or do I have to stay with the floodlamp?

I would appreciate any assistance

There are E26 to E11 converters. That would allow you to use a Halogen bulb. I can guarantee it will work but that might be an option.

So am I correct to assume the only bulb that will work is the floodlamp medium base 100watt 12volt R20 that I purchased from my local shop (which isn’t bright)?  Or is there another I can order?

The 100w r20 12v bulb is the only option for your light.