Hello All,
Thank you for your responses. I thought I would provide an update to hopefully help people in the future.
After I determined my charge pressure was low, and tried all the quick fixes (new filters, cleaned strainer, bleed air, etc), I still had no luck. I ended up picking up a lightly used HST online. I installed it (took about 4 hours to get everything apart and 6 hours to get everything back together). Also cleaned and put new boots on the propeller shaft joints and replaced the fan. I would recommend doing these things as they are cheap and easy while you have everything apart.
Once I got everything reassembled, I checked the charge pressure and it was back within spec.
Long story short, it looks like the problem was internal to the HST. I am going to tear down the old one to see the exact failure mode when I get a chance. My suspicion is that the unit got too hot; the fan was intact but there was a ton of mud and dirt caked on the HST, so I知 sure the heat transfer was not very good.
Overall wasn稚 a bad job...much easier than it looked. The hardest parts were a few spring pins that were corroded in place. Other than that very manageable DIY project.
Thanks,
Tom
