Try
www.moyerelectronics.com. They have a lot of old stock parts and might have this. I tried to cross the number on the NTE website; and, all it says is NTE-NLA. There must have been an NTE sub for this at one time; but, they no longer list it. If I can find an old NTE book around here, I'll look it up. Generally, I don't like to use NTE parts in deflection circuits (I've learned the hard way that they don't always hold up). In this case, you may not have a choice.
I'd consider replacing all the electrolytic caps in the vertical circuit as well as verify the supply voltages to the IC. Bad caps are usually what takes out the vertical IC.
Somewhere in the back of my mind, I seem to recall this IC being used in an early '80's Sony TV that I fixed about 10-12 years ago. The part was obsolete then; but, I was lucky enough to have one on a junk chassis.