Laserdisc,
Here is a link to a Triac's that will work great in your Zenith. I was a repair tech working on Zeniths for years and the Triac you want to replace is a very generic part,. Hope this helps:
https://www.ebay.com/itm/10PCS-BTA16...4AAOSw32lYroTn Or cross this number to a NTE number.
Dennis