Panasonic CT-1310M keeps blowing horizontal output transistor

[luRaichu]

I recently picked a Panasonic CT-1310M off the street. It's a commercial color CRT which accepts composite through a BNC jack and also has a VTR connector on the back, yippee! No listings on eBay for this model, barely any Google search results.
Once I got inside I'd noticed the 1.5A-125V fuse was blown so I replaced it, only to find it blew again when connecting mains power right after. Turns out the old HOT (Matsushita 2SD517) was blown & shorted out; I replaced it with the exact same part (new), left the TV set on with no signal (white screen) for a few minutes and the new HOT blew too. At that point I had one good HOT left since I ordered two. I replaced the HOT again but it blew once more when I tried adjusting the focus knob with the set still live.
Why does the HOT keep getting killed? I am currently waiting on a shipment of two new HOTs. Once I install another HOT I'll replace the safety capacitor for good measure and HOPEFULLY the HOT won't just blow again. Also it'd be nice to have the Sams' Photofact/Computerfact for this model as well.