Forget the bike shop.
Maintenance and part replacement is easier (or at least possible) if you have the right tools. Birzman's 1/2" Ratchet and Socket Set is designed to handle your hex, Shimano bottom bracket, Shimano HG cassette, and Shimano MF Freewheel needs with an assortment of chrome vanadium steel sockets and bits. Each bit snaps easily into the 1/2" ratchet head, and the reversing switch lets you ratchet in both directions, so you're never stuck. This set also includes a 1/2" extension bar to give you a little extra reach into those tight spots.