I would definitely say your problem is with the second gear synchronizer. You can double clutch to make it work. Shift out of third to the neutral position, let out the clutch, give the gas pedal a tap to bring the revs up then as you are putting in the clutch, shift immediately into second. The revs should be about the same as they will be in second gear at that point. You could also try driving with the the idle pulled up quite a bit using the throttle. I used this technique last summer while I had bad synchros.
