Troubleshooting the 6LE8 color demodulator

[trinescope]

I'm trying to repair weak color on a Motorola TS-918 chassis with weak chroma. The chroma signals to the separate grids of the 6LE8 demodulator are good and can be varied beyond the level given in the schematic, so the color IF section is most likely OK and not the source of the problem. The 3.58MHz at the cathode and G1 is a different story, however. The schematic shows roughly 10V P-P of mostly continuous 3.58MHz signal at both electrodes, but I have what looks like a short burst followed by a few volts P-P of 3.58MHz. The output signals are very low and consist mostly of 3.58MHz "grass" on the scope. The DC voltages are all within reason. The 6LE8 was the only tube in the color section I did not change out; I'll have to wait until next week before I can order new ones. I had a book years ago describing how these circuits work, but no more and I don't remember anything. I don't see how only a cathode and grid make an oscillator here. Perhaps this set is a ringing crystal setup similar to what GE used on a lot of their designs and I just have a dud crystal, and just enough 3.58MHz is being created by the tuned circuits to create the color signals. The crystal seems to be in series between the burst amp and demodulator.