There should be a sight glass on the side of that Boiler. You need to keep the water level above the Minimum boiler water level ( should be a sticker on the boiler or the measurement will be in the manual)
Is there a make up water feed on this boiler? Is it turned on?
Also do you have Low...
THis is a great thread to put up a first post lol. I joined to look at all the garage pics but i'll be around more often and will keep an eye out for 3/8" fine tooth as well. Thanks guys..