Hopefully after all is said and done, there is a better (clip) way to secure that BLUE cable. (Ziptie? FTW!!!!)
I don't know how well a zip-tie would work. The blue cable has a groove in it that matches up with a ridge on the inside of the clip. this is what secures the outer jacket of the cable so that the wire can slide inside when the lever's moved, rather than the whole thing moving. If you could zip-tie it tight enough it might work, but getting the zip tie through the slots the clip fits into would be another hassle since you'd still have to get to the top of the heater controls. Hmmmm.... some bailing wire might work better as it might fit into the groove on the cable and you can bend the end into a U-shape so you could feed it up through one side of the clip hole and then pull it back down through the other side.
Where are you located? I have an extra clip, it's the first one that I messed with to see if it would come out from the bottom so it's a kinda beat up but it might still work for you. Let me know if you want it.
Well that's mighty nice of you, thanks. I'm in Seattle. PM incoming.