[Boatanchors] HRO-50T Help Needed

[Joe Connor via Boatanchors]

I need some help confirming my troubleshooting on this receiver. I recapped it and aligned it several months ago. It worked great until last night. Here's the Rider schematic:
http://www.nostalgiaair.org/PagesByModel/395/M0012395.pdf

Last night, it suddenly lost strength and sensitivity. Signal injection showed that the problem was in the IF stages. An IF signal injected into the grid cap of V-6 (2nd IF/6K7) produced a strong signal. An IF signal injected into the grid cap of V-5 (1st IF/6K7) produced a weak signal. An IF signal injected into the plate of the 1st IF (V-5) produced a strong signal.
I checked voltages and there was no plate voltage on V-5. The plate voltages for V-5 and V-6 are fed through R-17, the plate filter resistor. R-17 has plate voltage as does the plate of V-6. A resistance measurement from R-17 to the plate of V-5 showed an infinite reading. 
As I interpret those readings, it looks like an open primary in T-6, the 2nd IF transformer. Does that make sense? Does anyone have any other ideas? What puzzles me is how I can get a strong IF signal through the plate of V-5 if the primary of T-6 is open. I'm wondering what could cause it to open so suddenly. 
If you all agree with my diagnosis, I plan to remove T-6 and, hopefully, I will find a break that I can repair. Of course, if anyone has a spare T-6 lying around, I would be interested in buying it. I suspect, however, that will be like looking for the proverbial needle in a haystack.
As always, thank you for your help. 
                    Joe Connor