740 heated seats

Both seat heaters have stopped working. The illuminated switches however are both lighting up. Does this mean the seat elements need replacing or is there another solution?

The car is 1988/89, only done 85000 miles since new.

Check out the earths and circuit breakers in the fuse box first, then look at the control units under the seats, my guess if both have packed up that the circuit breaker or earth is the problem

Many thanks