When my Transfer Switch went down I decided to replace the entire unit.
After I replaced it, then I decided to figure out what was wrong with the old one. What I found was the Time Delay Module circuit board had a burnt "hole" in it. So I decided to order a new circuit board/Time Delay Module, and installed it in the old switch. I then tested it with a test wiring setup and it works great. So now I have a spare in case it is ever needed.
I have found the best way to make sure something doesn't ever break down is to carry a spare.
I found Solar Seller to be a great company to deal with. You are correct, the cover on the original Iota switch was a real bear to remove. On the replacement it was redesigned and much easier.
The swap of the transfer switches wasn't that hard. I believe it took me about 30 minutes.
Ron