cylinder leak down test, you can use a compression gauge in the spark plug hole for each cylinder and then do the leak down test on any offending cylinder if any. Though the head will be coming off regardless if you find a cylinder with no compression the leakdown will give you more clues on what is...

There is a sleeve that pulls up and locks the hose when your'e trying to pull it out, you have to push that plastic ring in the grommet back in while pulling the hose out.