Spa heater issues after overheating

[dmtinker]

I have a Raypak spa heater which is at least 25 years old. The circulation pump stopped due to the timer but the heater was left on for at least 2 hours. Consequently, it blew out a pressure fitting which I had to replace. Since I got it up and running, I have noticed a pressure loss in both the pool and spa returns. My suspicion is that something internal to the unit melted/warped/got bad juju. it isn't leaking and just wanted an opinion on likely internal damage that may be causing this.
Thanks in advance.