If that is the cap that fine tunes the PLL, be sure to use a digitally tuned receiver, as an analog receiver's AFC will chase your frequency.
Better still, if you have a friend who's into CB or HAM radio they might have a frequency counter that will show you what frequency you are on.
If they have one you can borrow, do the following:
Program the transmitter to your desired frequency.
Tune the cap until the PLL locks (if it isn't locked).
Disable the stereo pilot as that will skew your frequency reading.
Using a plastic tuning tool, turn the cap slowly in one direction or the other while watching the frequency counter. If the numbers are moving in the wrong direction, turn the cap in the other direction. It should only take a few minutes to get back on frequency.
But if you can't get a frequency counter, using a digital tuner should get you close enough.