'89 Zenith No remote function?

[zenith2134]

This is the 20" Mexican Z that I posted about a while back. The CRT is holding up well enough, and it is an IR-ready set. Problem is, I've tried 3 different universal remotes and none of them program the set. On other sets they work fine. I even tried the codes for Goldstar just for laughs.

Now, I don't think I have ever seen a bad IR detector or IC in any tv but it's certainly possible.

Not that the set's worth it, but I might wanna dig a bit deeper and see what's up with it... Any ideas?