Jim,
I am pretty sure you have the Johnson 1000 gph bilge pump with the Ultima Switch. The whole assembly is for sale on Amazon for $88. I say this not just because we have the same boat, but a bit more than a year ago I broke the flange that keeps the sensor attached to bilge pump. It is a weak link in the design. When you try to get the sensor off to clean it--which you have to do or it misfires (in my case it wouldn't shut off once started)--this weak little flange easily breaks.
And of course, getting the new base with the built in flange is a royal pain so I just got a full assembly and now how two spare bilge pumps.
The hassle, as you well know, is putting the base with the flange back in. There should be three screws, if memory serves, attaching it the bottom of the bilge. For a short, squat--add ugly--guy like me it is a royal pain to get those screws out and back in. But once done, you can put the pump and the sensor back onto the bracket and you're good to go without rewiring anything.
I finally resorted to using a cleaner-soaked cloth on a long stick to do the cleaning and have avoided breaking the flange.
Best of luck! Find a lanky teenager to do the work for you.
Jeff