Further to my previous question, I also noticed that the crystal there was a 12MHz where this should have been 6MHz (due to an inventory error - the wrong part was fitted). I've removed the 12MHz crystal and fitted a 6Mhz crystal using a hot air tool but now it doesn't oscillate. It kind of looks like it's trying - the scope shows a fair bit of noise and occasional flashes of what looks like about 6MHz waves but it doesn't oscillate stably.
As far as I can see, the major difference is that the 12Mhz crystal has 40 ohm ESR while the 6MHz crystal has 80 ohm ESR. As far as I can tell, my rework hasn't damaged anything - the load caps and series resistance are still doing the right things - but it's a bit hard to tell if I've damaged the crystal or the IC.
What is my most likely problem here? Is the higher ESR of the lower-frequency crystal likely to be a problem? Or is it more likely that I have damaged a component with my rework?
The crystal has a 1.5k resistor in series with it (cribbed from the TUSB2046B reference design). I'm tempted to short this out to try to reduce the losses in the oscillator and see if that improves things - is this a useful thing to try?