Graybeard, it sounds like regualtor, but did it ever charge?
Ive got a dvr2, works fine, but i must confess i nearly ruined it, after i got the charging going, by connecting the battery the wrong way a bit later during the resto, lucky for me the dvr2 has inbuilt protection against that school boy error, but not all electronic regs will have that protection i guess......i dont know about the wassel unit.
By the way, your symptoms might be consistent with the battery the wrong way round.......and if you have done that it may be necessary to flash the field winding.