That tank is held in place by 2 metal straps on each end of the tank.
It's pretty simple to loosen/disconnect the straps, lower the tank and
you have easy access to the gas, via the hole after removing the pump
assembly on the top of the tank.

You can disconnect the fill pipe/access, about 15" past the cap (half
way between the cap and tank), behind the fender/wheel well. There is
a rubber hose, inside the pipe, that needs to be removed, then the
tank can be syphoned (after reassembling the pipe, if you want to).
If you try to replace the rubber hose, it will kink, and subsequent
filling of the tank will take forever, as the gasoline tries to flow
past the kink. Those rubber hoses are inserted into that pipe in a
special way.

I would think the switch, for transferring from one tank to the other,
is bad, not the pump.

Sonny