Just to repeat Mstrkey slightly, you can use oil or grease on the rammer housing. However please only use oil on the rammer itself.
I think you may have been unlucky with your leak, when reassembling the Rammer Housing for the first time it's possible that you caught the valve spring and bent it, which would cause your exhaust valve to remain open and leak.
Upon reassembling again this time with grease, you managed to miss the spring and fit it correctly, causing it to not leak
If you do ever reassemble and it leaks, shooting one shot will normally correct the bent springs position and stop the leak, leaving you good to go