Before going any further I would check the power.
Try flipping the breaker off/on slowly a couple times. Sometimes you can loose half the line without actually tripping the breaker.
Check the voltage at the plug
L1 to L2 should be 240 volts. This is the voltage for the heating coil.
L1 to Neutral and L2 to Neutral, both should be 120 volts.
Unplug the unit and check the wires at the terminal strip in the machine to make sure none are loose or burned out
Check the power at the terminal strip.
Do this with the heater off and on.
Be careful as 240 volts is lethal !!!
FYI: Using the frame/ground/Neutral to check power for the heating coil can give some useful info but also can be confusing.
You said " tested the heater relay at N.O. and COM and they both had 120V with dryer running (I guess thatís OK but can't find a spec on it)"
This does not tell you that the relay is OK.
If the relay does not close then you see the L1 voltage (120) at the NO contact. Also you could see the L2 voltage at the Common contact if the rest of the heater circuit is OK.
If you disconnect the COM contact and use Neutral as the reference point then: With unit off NO should be 120 volts, COM should be 0 volts
With unit on NO should be 120 volts, COM should be 120 volts.