I have a 3-zone system. Two area heating and one hot water.
The zone valves are honeywell V8043E1012.
The area heating zones work fine.
The hot water zone valve receives signal from thermostat OK and opens
The water flow valve.
However, the boiler and circulator do not receive the signal to fire up.
When I touch the red lead wires from the valve switch, I hear a connection
Being made and lost, as if there was a loose wire.
Does that make sense? Is the Aux. switch accessible to check these connections?
Or does this mean the entire valve needs to be replaced?
Thanks.

Here is a link to your valve

http://customer.honeywell.com/TechLit/pdf/60-0000s/60-2133.pdf

Yes there is an end switch in your valve.
Yes it is replaceable BUT you will have to go hunting for a replacement switch since most supply houses only have the complete valve OR just the power head.

You can test the end switch with a meter or as I sometimes do just jump the end switch wires. Now you have to make sure the valve is open before you jump the switch leads because you do not want your circulation pump to come on without a valve open to relieve the pump pressure. Sometimes I just flip the manual valve lever to the open position or activate the valve by the thermostat then jump the switch wires.

I usually replace the valve since by the time the end switch goes bad the little shut off ball is bad but you do not have to as long as the valve was working OK before the switch went bad.

I believe the switch is made by CHERRY Switch Company if my memory serves me correctly.

If you replace the power head you will probably have to drain the system and that can be a pain to refill so if you buy the power head or the valve you could take the switch out of the new valve and put it in the old valve as long as Honeywell has not changed the switch style.