I had a shorted light fixture, and not knowing a whole lot about them, had the pool company come out. They replaced the bulb re-assembled the light.
It's working fine, but the pool company told me they didn't replace the nut and bolt on the tension ring. I'd expected them to be a bit pro-active - but now they tell me they're special parts, and will come back out and replace them, at a cost of $25 -$75 for their time, plus parts.
Can't I just pick up a brass bolt, nut and washer and diy this?