PinchRoller

I agree with Brian that Panasonic capacitors are good replacements. I did see that the model Brian used is out of stock at DigiKey. I did do a search at DigiKey and they had six ones that had outstanding specs: One of those parts, Cornell Dubilier / Illinois Capacitor #477KXM035M had a great lifetime rating and a high tolerance to ripple current at 120Hz. it only cost ~ a buck. -Pinch

On this version, there is an opto-coupler that effectively controls the coil using the 120V line. Here is the schematic of that circuit: Keep in mind that this product uses an inverted power supply, so one might be alarmed at the switching of the neutral line. I do recommend checking the two capacitors around the relay for possible shorting, which would keep the load on up to a certain current. -Pinch

I agree with stillwater, the issue may be a broken relay. That ApplianceLinc and many Insteon relay products used model #TRV-24VDC-SC-AL from a company called Tai-Shing Electronics or TTI. That part has been replaced with TRVF-24VDC-SD-AL. The spec are 22.3 x 16.3 x 11mm, 24VDC @8.3mA coil and contacts rated for 250VAC, 16A, TV-5. A drop in replacement is Massuse ME-23-24P. There are many relays that match those specifications on DigiKey, Mouser, and others. Another possibility is the capacitors across the high-voltage switched contacts have shorted. Caps sometimes break down when attached to some loads, which produce a high voltage reverse EMF upon relay opening. This can be tested with an ohm meter or continuity tester placed across those capacitors near the relay. Good luck, -Pinch