I assume the switch you flipped is for the bilge pump? If so, they are fused. See if the fuse has blow,. if so, tap on the motor a bit. Sometime they get stuck and just need a little love tap..
With many mechanical items, there are tricks of the trade. One of them is putting the pump in the freezer for 30-60 min to allow the ring to contract. It then pulls out with no cutting or impeller removal needed. For doing it yourself it is great, but I now see the OP is having a mechanic do the work, so I'd probably get the tool rather than 'pay the man' for the extra hour.
Yea it's true by its a lot easier to remove ring with the impeller out. Even when u freeze to take out wear ring and freeze new one to put in the clearance from wear ring and impeller is so little makes it hard and tight to get it out and in