[N2KZ]

I am restoring a Philco PT-2 radio from 1940.

I have a problem.

When I tune below about 800 kcs, the radio goes into motorboating oscillation
but still receives signals to a degree. 

There does not appear to be a short in the vari-cap. 
The motorboating effect changes with tuning and the vari-cap does not seem to short out.

On the Rider print for the PT-2, there is a IF trap filter at point 5.
When I lift that filter from ground, the set will motorboat all over the dial regardless of frequency.

I should mention that I have replaced the paper capacitors with Sprague Orange Drops.
I recreated the winded coil over the .2uf 400 VDC capacitor as part of the IF filter.

I have tried connecting the antenna coil built into the cabinet in both directions with no improvement.

The 7A8 tube tests good on my military surplus TV-7 tube tester.

Can you suggest anything I can try to cure the motorboating?

Attached is a picture of my recent rebuild as it looks today.

Thank you very kindly for your time and consideration.

Karl Zuk  N2KZ  Katonah, NY