RBM (remove this) wrote:
: Thermostat
calls for heat, sending 24 volts to it's respective zone valve- when valve
completely opens, it closes end line switch which closes circuit to aquastat
relay on boiler which fires boiler. Boiler runs until thermostat is
satisfied or reaches high limit

OK now it makes sense. I have not dealt with these valves in a while.
Its wired this way to ensure that the boiler does not fire up until the
valve is opened. Then what your repairman did is bypass this end line
switch out of the circuit so the boiler can fire up. Plus it was
necessary to manually open the valve.
RBM is correct, you should have both valves replaced.