Echo Base LFO problem

[m-theory]

This has me puzzled.  I built this, mounted it up, and it's worked perfectly.  Last night, I gigged it, and it worked flawlessly throughout the night, until it suddenly developed an out-of-control oscillation feedback, and I had to take it out of the signal path entirely, because the feedback continued even with it switched off. 

When I plugged into it today to see what it would do, the feedback was gone and the delay works perfectly, but the LFO no longer does its thing.  I can hear the warbly pitch shift when I turned the depth knob, but no matter where I set that or the rate, nothing changes. 

I opened it up to find a ground wire hanging by a thread, so I repaired that.  While I was in there, I also wired up the SPST switch for the LFO, which I'd previously left out.  I also swapped the TL072, thinking that perhaps that had gotten damaged somehow, and swapped the PT2999, since I had a spare lying around. 

No changes...LFO still doesn't do its thing, yet I get the warbly pitch change when I move the depth control.  Additionally, and very odd to me, is that the switch doesn't make any difference whatsoever, although the switch checks fine. 

Something in that LFO portion of the circuit isn't right, but I haven't a clue where to look.  Any ideas?  What could typically cause something like this? 

http://musicpcb.com/pcbs/echo-base-delay/

[mth5044]

Get out the old multimeter and see if you are getting any voltage oscillation. If you aren't getting anything wobbly, then something in the LFO has clocked out. If you have wobbly, make sure it makes it to the PT2399.

[slacker]

Good advice. The LFO stops working with a low supply voltage so make sure you're getting a good 9 Volts to the board before doing anything else.
When the LFO worked did the LED flash? If it did and it's not now then it means the LFO isn't running, if the LED is flashing then something is wrong between the LFO and the PNP transistor.
If the LFO isn't running then the LFO kill switch won't have any effect so don't worry about that.

[m-theory]

Oh, for cripes sake...I didn't even think of the battery...I guess 6.4v isn't quite enough to run the LFO!  Fresh battery, and problem is magically solved!  What a maroon! 

Thanks!