This is a small ceramic disc capacitor (that's broken in half) in the horizontal oscillator section of a hybrid European-made B&W set.
https://i.imgur.com/TnORyRU.png
If I'm reading this correctly, it's an 1800pf capacitor. Is that right?
Next question: is it OK to replace this with one of those cheap polyester film caps you get in the "1000 capacitors for $10" packs on eBay of the same value? Or does it need to be ceramic? It sits right next to the horiz output tube.
For those interested, the TV is branded General Electrica Espaņola on the outside, and Miniwatt on the inside. Made in 1969, Miniwatt was owned by Philips and as far as I can tell made CRTs for them. But evidently they also made entire TVs, in this case sold under the GEE name. I've also seen this same set for sale here on second hand sites under the Emerson, Koster, and Iberia brands. I've been unable to find a schematic so far.
Thanks for any insight!