Kris,
Can’t get 62300 to come up on any of my systems. I can find a 6200, a 62600 and a 623D. Is this a UK machine? If you could find the PNC or ENr number it may help.
General advice with heater is that it should read 20-30 ohms when disconnected from the wires. Do this with the power off! There should be no earth leakage. Most AEG machines use a relay to switch the heater on and off. On older ones this was a separate unit, late machines have it as part of the control board. You could check for dry/burnt solder joints there.
If you’re not confident, get professional help!
Regards,
Penguin45.