piston with a little gauge

[johnny70hp]

One of my pistons has a little gauge on it, The marine i brought it to says there's no compression on it, Now I have someone who works on small engines/outboard coming friday to see my engine,but he told me to get a new head gasket so he can check out the compresion on it, Now the gasket is going to cost me 50 bucks with tax on it, my question is it worth it or is he going to tell me what the marine said,that i need a rebuilt, I'am hoping I don't need a rebuilt, times are tuff and just looking to finish off the summer boating away, can someone help me out please, thx