Thank you to all who replied!
Well, it seems that my best option is to have my C-5 repaired. Especially since it's only located about 1 hour away. I think I will take both the C-5 and the TFM-45 in and have them gone through and brought up to spec. Those two units have served me well for 20 years and I do like them so I guess I will treat them right and give 'em a "tune-up" and repairs.
Thanks, rdgrimes, for posting that link to the service facility. I will call them on Monday and see about dropping off both units soon.
As for turning on the amp with a remote...I'm sure there is a device out there that the amp can plug into and has a remote receiver. I think I'll post that question in the Harmony One thread and see if anyone has some ideas.
Thank again to all who took the time to provide sound advice.