I don't know your particular application but the hose/tube is typically:
Located at the top of the crankcase, may or may not have some type of one way check valve installed, might be routed towards bottom of engine,
And terminates to nothing (ie...vent).
With what you stated (leaks only when running) I would just verify cc vent is clean and venting before randomly changing gaskets and seals.
Thanks. It's an old Honda Fourtrax that they only made for 2 years so it's difficult to find much info on it. I finally found a pdf service manual, and it looks like 2 in the diagram below so I just need to remove the gas tank to access.