Minor damage to the wires can be repaired by yourself.
Examination
1. Turn on the ignition and heater.
2. Put a folded strip of aluminum foil on the voltmeter probe and press it with your finger against the heater filament.
3. If the voltage at the center of the thread is 6 V, then the thread is good; if the voltage is 12 V, then the thread is broken (break occurs between the center of the thread and the mass). If the voltage is 0 V, then the thread is broken between the center and the supply terminal of the heater.
4. If the threads are good, then connect (-) heater outlet with ground. If the voltmeter reading changes, the ground connection is poor.
5. The place of a broken thread can be established by leading the aluminum contact on the voltmeter probe along the thread away from (+) output to (-) heater outlet. (-) connect the output of the voltmeter to the aluminum contact. At the break point, the voltmeter reading should increase from 0 to several volts.
Repair
1. Splice broken heater filament with Dupont N 4817 conductive epoxy or equivalent.
2. Turn off the heater and wait until it cools down completely.
3. Carefully polish the damaged area with a steel sponge and wipe with alcohol.
4. Apply a mask of adhesive tape to the damaged area.
5. Prepare the resin according to the instructions.
6. Apply the composition to the gap in the mask, smearing approximately 18 mm in both directions.
7. Remove the mask after 24 hours.