Issue with my ss4

[IndianaChristmas]

I have pulled out my ss4's for testing. I have found two that will light channel 1 but the others don't light or will occasionally flicker when I plug or unplug the light string.
Any ideas?
Thanks.
These units have all the components to be full controllers but I have them set up to be ssr only.  All wires have been double checked as well as solder joints.

[dmaccole]

It's it's the optos or the Triacs ... take a known working optocoupler and switch it for one in a bad channel ... if the problem persists, the problem is with the triac; if the problem goes away, then it's the opto that's bad.

\dmc