Washer Pump Replacement

Hello. I have Thermoguard on my battery that doubles as a windshield washer reservoir. I am attempting to replace the washer pump motor on this piece. The factory service manual says to cut an access hole on top of the Thermoguard to access the nut that screws on top of the washer pump. I'm not too keen on that idea and was wondering what other people have done to replace their washer pump? I've attached some images of to show what I'm dealing with.

Can you bend up a cheap wrench or socket extension to reach the strainer nut through the fill opening? If so 2 people could hold the nut and unscrew the pump assy. And reverse the procedure.
Mike

You can try "rebuilding" the pump in place.
Uncrimp the motor housing from the pump housing and swap out the motor. This is assuming of course that your pump housing is ok. Otherwise, a deep 7/8 socket and universal joint should work.

Thank you both. The 7/8 socket is a good idea. I was also thinking of a flexible grabber tool perhaps.