I just recently picked up a Free Spirit fs12 for really cheap as a beater bike...

The bike has a pair of stem mounted shifters, they are a bear to shift. I'm trying to diagnose the cause. I've taken them apart brushed off any rust marks, WD40 the pieces, and put back together. The derailluers seem fine, they move with ease.

I'm thinking its 1 of two things, just a horrible setup or the bike needs new housings and cables?

This could also be the nature of the shifters, I've never ridden a bike with stem mounts before.