Our pool is between 8-10k gallons and was built in 2008 (it came with the house when we bought it in 2016.) It has a 400 btu Pentair propane heater (pictured.) It worked well for several years but in 2020 we kept getting an r=8 code. The heater still worked but we had to start turning it off at the breaker when we were done; otherwise it'd just stay on. We had someone come look at it and tell us we just needed a new panel for it, but we never got around to replacing it. Now when we turn it on there's a clicking noise followed by a few shudders, and it's not heating. Two questions: is it beyond repair? Also, if we get a new heater, isn't 400btu overkill for our size pool? Recommendations on size of heater and brand would be appreciated. Many thanks for any advice you can offer!