I want to try and clean this with out taking the paint off and clean the cylinder. What is the best way? Thanks for any ideas.

One more pic

For the cylinder---plug the outlet and fill the cylinder with a mixture of CLR and water, and let stand overnight. Next day, drain and flush with clean water. I have also used Oxy clean with good results.
I usually just use a pressure washer on the external sheetmetal.

I filled it up with CLR/water mixture, let sit about an hour, scrubbed what I could with a toilet brush, gallon indicators were in the way. A small seepage formed at the bottom in the gasket material and as I was dabbing it with a paper towel, a major leak happened as I must have loosened the gasket. I had to drain it quickly, good thing I had 2 buckets ready and a hose connected. After rinsing and drying, I rigged up a 5 inch piece of zip tie (wide one) with a gun cleaning patch taped on the end and wiped the areas in front of the gallon indicators which were still dirty. It flexed just enough but was still somewhat stiff and worked perfectly, but required patience and a long arm. I am or was a Montana bottle collector until I started on petroliana, and this cylinder came out so clean it would be described as attic mint in the bottle collecting field. No glass sickness at all, and the swirl pattern in the glass is awesome. It reads MACBETH, KROMEX, MADE IN USA. Now I am really hooked as this is my first visible thanks to Scott. Are you holding P.A. Meetings (pumps anonymous) at your house Scott? That would be like having an AA meeting at the bar.