Power Mirrors

I just bought a 01 Chey Silv. 2500hd Ex cab, It has power mirrors but the diretional pad to move them only let me move them up. I,m thinking the electronic contacts are shot but I don't know.

Does anyone have a clue what might be wrong? or do I need to just replace the switch? And where is the best place to order parts like that?

Thanks.

gm dealer is the best place to buy parts, but you might just try a junk yard to see if you can find a switch so you don't have to wait on parts to come in. Both mirrors will only move up, or just one?