steady flashing channels

I had this weird problem with some Renard SS16's last year and now it seems to be happening again this year on a couple of boards.

I have a couple of channels(I'm up to 3 on one board) where I get a steady flashing on some channels. The lights will turn on for about 15 seconds, then off for 15 seconds, then on, etc.

All of these boards were built using the group buy triacs from about 3 years ago...I plan on replacing the triacs with the latest recommended ones but it just seems weird that it's such a consistent flash.

Has anyone seen anything like this? I'm thinking it's triac related and I'm going to test my desoldering skills on a board tonight.

Thanks,
Chris