Electrical drain?

[Yankee]

I have a 6 volt positive ground system with original generator and cut out - no alternator. I have replaced the battery about one year ago and since it needed to be charged in order to start. Ammeter shows appox. +4 when driving and -20 (pegs to left) with lights on in any position. I believe there is a drain somewhere, but all the connections appear to be tight. What do I check next?