I have the same CRT in my FADA, but it's hooked in differently, the cathode on mine is grounded, and video fed into G1.
The voltage readings for each pin on yours is listed on the SAMS, also you need to be sure you have a good video to the cathode, not sure what it will be for yours, but mine was about 39v PtP, my guess yours should be about the same, but inverted, since its going to the cathode, as opposed G1 on mine.
You also need to find a way to check that you have good HV, if it is low, it may be causing you problems, and/or a misaligned / weak ion trap.
But however, if all checks nominal, you most likely have a very tired / dead CRT, and must find another, and most likely end up paying way too much to some fool on Ebay, like.
https://www.ebay.com/itm/Vintage-Syl...-/174589841825