Help me repair my cob light please

Help, I have a cob panel with four cobs wired in series with the driver shown in the pic, this light has been a work horse for me year after year anyhow one day it just went dark, I have power to the panel, I've tested that with my volt meter, my question is how do I test this driver? Do I set my volt meter on DC 238 volts and test across the positive and negative on the driver? If it's a cob that's burned out is there a way to test that with my meter? Maybe set on ohms resistance? Anything else I should check for? Thanks much

Yes, test voltage across positive and negative leads from the driver. If there is no DC power, check to be certain there is AC power to the driver.

A dead cob can be found with a jumper wire across one cob at time, when you get to the dead cob the jumper will complete the circuit and other three will light up.

That makes good sense thanks, I'm guessing the momentary increase in voltage across the three remaining cobs won't hurt them if it's brief?