I hope that you ordered a package of fuses, usually 5 to a pack, because if there is an actual component failure that is not repaired, the fuse nay fail a second time. Transient voltage protection devices often protect and become permanently low resistance. So after you replace the fuse, but before you apply power, use your resistance meter to measure the resistance across the mains power connection, with the power switches on.
If the resistance is just a few ohms then probably the problem remains and the transient voltage protector device must be removed and replaced, or just not used.
Some folks here are able to recognize the TVS in a photo of the circuit board. It may be near the fuse that you found.

ok, thank you. Yes ordered a couple just in case (shipping prices are nuts!), I do know how that goes . There was a bad triac I had replaced on the ozone rail but missed the fuse somehow. I'm a bit hesitant to test under power as this is a high voltage device (1000v) & not looking to have 'a really bad day'. Here's a pic showing missing fuse & where triac was replaced in the 'ozone control' section.View attachment 293596
Yes, that's what I am hoping was the cause for the fuse to blow - bad triac. I went through every component and they were all good, there wasn't anything obvious so I'm hoping once I put the fuse in next week and fire it up, the ozone plate comes alive & there's no 'magic smoke'.OK, now it gets interesting because the section where the triac was replaced is fed from the section where the fuse had failed. That is the section that has the connector for the Ozone system. So I suggest giving the ozone portion a close examination, given that both a triac and fuse in the power supply were damaged.
I was suggesting an examination of what was beyond that connector. Also, if that high voltage portion does not seem to be functional that could be part of the problem.Yes, that's what I am hoping was the cause for the fuse to blow - bad triac. I went through every component and they were all good, there wasn't anything obvious so I'm hoping once I put the fuse in next week and fire it up, the ozone plate comes alive & there's no 'magic smoke'.