Yikes! Yes, you need to use non-polarized caps. They stopped using PCBs in caps a few decades ago so no worries there unless you dig up some ancient ones.
I used a plastic film motor run cap like this in my Predicta Holiday. I've used regular film caps too, but I'm not sure how well they'll hold up under extended use.
http://www.digikey.com/product-detai...9401-ND/207387
