There is a "heavy duty" thick, white, double-sided tape for hanging pictures etc that works well. The backing tape is red as opposed to the white backing tape for the "regular strength" tape. The clear tape didn't seem to work as well and it's the devils work to get the clear backing tape off of it. The fittings like you describe that I have used it on have stayed stuck. WalMart, I believe. Scrape the old stuff off and put this on, cut to size.
Loctite makes a clear adhesive called Power Grab that STICKS things. The wiring, including the power cables and GPS antennae cable that comes from the aft area of the fuselage, has been stuck in place along the underside of the stringers with something similar and, changing the antennae cable recently, had to work hard to PRY it off of the stringer and curved underside of the bulkhead. I put it where I did not want to diminish the strength of the stringer by drilling holes and all aft of the baggage compartment, not in the cockpit. The Locktite stuff sticks NOW and cures in 24 hours. Be prepared to work on it if you have to relocate the cables you use it on.
ClickBond is wicked strong as well. Especially if the part is never going to move.......!