I'm trying to make a simple Hartley VFO. I've made one before no
problem, but this one won't start, period. The only difference between
this one and the last one is that I used a T50-2 core instead of an air
core inductor. Is that likely to kill it?

Also, last VFO I made, I tested it by feeding it and a signal generator
into a product detector to listen for a tone, this one I'm trying to use
a frequency counter to make things simpler. It reads crystal oscillators
no problem, and I've even used it to read a VFO in another receiver, no
problems.