Ok, let's try and clear up the confusion.
The difference between 36V DC and 70V AC can only be explained by a measurement error - the 70V is wrong. 36V would be just right if the transformer is 24V AC, which it probably is.
The delay heater coil is in parallel with the bell. The low resistance between B and C is because you're measuring a closed contact. The coil resistance can be measured between A and B, or A and C, but for one of those - probably C - the connection goes through the break contact, and pushing the probe on the terminal may disturb it and change the reading. I take it you disconnected the bell before you measured, else you're measuring the bell in parallel. Any resistance measurement through the delay heater is good, it shows it's not burned out.
You can't take resistance measurements with the power on!
When you hit a winner the circuit is closed to energize the bell and the thermal delay. The payout relay is shorted out by the delay contact and does not operate. When the delay heats up and opens, current flows through the coin slide home contact, the payout relay and the bell, though the current should not be enough for the bell and the delay to keep running. The payout relay latches itself on and sends power to the coin slide and the left uniselector, which pulls in but doesn't step yet. The coin slide moves and opens its home contact, but the payout relay is now latched on by its own contact. When the coil slide drops the coin it opens its end of stroke switch, which drops out the payout relay. The coin slide then drops back, and the left uniselector steps. If that was a 2 coin payout, it steps off the payout circuit and we're done, otherwise ... By this time the thermal delay may or may not have closed its contact again. If it has, the same cycle repeats. If not, as soon as the coin slide hits the home contact it re-energizes the payout relay for another step. UNTIL the left uniselector steps off the payout circuit.
The point here is that the thermal delay has one job, which is to delay long enough for the bell to sound and attract attention. You can remove it from circuit (but leave the bell in) and the mechanical delay of the coin slide going back and forth will accomplish the payout.