I am a sales rep in Michigan for Erie controls and I understand your problem. Erie makes an excellent valve that would replace yours. In fact, right now we're working with Western Michigan University to replace a bunch of Dole valves.
I would suggest that you strongly consider abandoning the Dole valves rather looking for them. The heat motor technology in those valves has been far surpassed by the modern electric zones valves. check them out at http://www.invensysibs.com/erie_motovalves.shtml
Let me know if you have any questions........ and by the way- these valves will cost a lot less than the Dole.
Mechanical Sales Co. LLC