for repairs and service try PhotoTech at 360 W 36th St in Manhattan, they are couple of blocks from B&H
also Camera Center 138 W 31 St in Manhattan
to buy stuff chems and film get them from B&H and Adorama (I go to B&H some people prefer Adorama)
I develop at home my B&W and color negs but for slides I go to LTI in 30th between Park Ave and Madison (
http://www.lti-lightside.com/)
They start the batch at 11 AM so drop your film before that and you can pick it at 3