I’ve done thruster work on a R25 and R29 and on both had a shop tear down the thruster with the R25 thruster being repaired and reinstalled and the R29 thruster found to be unrepairable.
In the pictures I was sent it appears that control wire you reference as appearing “attached to the front side of the motor” which I think you mean appears attached to the front side of the case? Isn’t attached to the case, it runs through the case on its way to its connections to the various sollinolids within the case.
That sloped plastic piece with a hex on the base at the wire entry point into the case is just the way they seal up the entry point of the control wire. On one thruster I unscrewed the hex head and within was just the wire going on its way to its various connections within the case, with the cap off you could pull and push the wire a bit but it was in no way a plug or connection.
Realise for a waterproof rating things have to be sealed up pretty good and for an explosion proof rating things have to be sealed up really really really good. On the one you’re just keeping water out on the other you’re keeping vapor out.
The R25 thruster I worked on was a 2006 model, the R29 model I worked on was a 2012 model and the one I replaced it with was brand new and all three had that funny little hex head sloped thing where the control wire entered the case you’re referencing so I don’t think anything has changed in this part of the manufacturing of the units.
Becha you trace that control wire again and you’ll find the plug someone referenced here, all three of the thrusters I worked on had a plug some feet up the control wire. Or you could unscrew the hex head while the thrusters still mounted and see what’s underneath there, likely just the wire going on its way.
By the by, the water getting in is first getting by the seal on the base of the switch leg, the outer part of the thruster assembly so you might try dropping it off first from the outside and resealing it prior to pulling the thruster motor.