Motorized Zone Valves-How to tell if they are open?

ViolinDoctor

I have a large steam system on a Mills oil fired boiler. There are 2 pipes forming the header one which splits into 2 and supplies steam to the steam coil in the basement for forced air on the first floor and the other which supplies steam to 6 radiators on the 2nd floor. The other pipe off the boiler supplies heat to the rest of the house which is about 16 radiators on the 2nd and 3rd floors. Each of these 3 pipes has a motorized zone valve on it. It is a 2 pipe system with a condensate pump. One night I awoke to sweltering heat. The zone valve that supplies heat to the 2nd and 3rd floor radiators was not shutting down, thereby sending a continuous heat call to the boiler. So ultimately what I did was power the valve open and leave it that way because I am convinced (thanks to Dan's wonderful books) that I don't need the valves anyway. Then another night another valve broke down, same thing, sweltering heat. I did the same remedy. So now I have the whole system running off the zone valve that supplies the steam coil with the other 2 valves open. So in essence, when the remaining valve opens, the whole system is open. The valves are Jenkins brand with a 150 stamped on the side. What I'm not sure about is if I have the valves open all the way. It seems like the radiators are taking a really long time to get hot and the heat from the forced air steam coil is heating those areas too much. How can I tell if I have these valves all the way open? Does any one have suggestions on getting better control of the heating system so there is a more even heat throughout the house? Or should I fix the valves or eliminate them all together?