Poor / cracked/ dry solder joints in the power supply diodes, Voltage Regulators (the 3 transistors in a row on the left near the relay as you look from the front top.). I'd bet on the Voltage Regulators. Reflow all the joints in the power supply area. The other thing it could be is if the lights come on and it just takes forever for the relay to kick in is that BIAS is way too high (non adjustable!)at startup and takes a long time to come down to a reasonable level for the relay to kickin or the relay controller circuit needs to be rebuilt. Usually a transistor and a cap.