[AMRadio] Strange oscillator?

[CL in NC]

I've got this old Regency R75 RX I am going through.  The LO operates at 455 below the signal freq. What type of oscillator goes up in freq when you back the slug out of a coil form, or down in freq. when you loosen a trimmer cap?  You can see this on a counter too.  I have one of the old tuning wands, powdered iron on one end, brass on the other, you put the brass end into the coil form and it goes down in freq, iron end into the form and it goes up.  I reviewed all my osc. circuits, but this one seems to defy the resonance formula.

charlie W4MEC in NC