So I picked up this 3 way secondary regulator. Does anyone know if these are just shut offs, or shutoffs with check valves? Taprite's website doesn't seem helpful saying either way.
Some do and some don't. If you happen to know the specific model, you can check http://www.taprite.com/pdfs/beer/Secondary_Beer_Regulators_SS.pdf.
Otherwise, just unscrew one of the shut off valves and try to blow back through it.