Hi Allen. This is normal for the 3340S. Not much you can do except make sure the sync head is good and clean..as all your heads and transport should be and demagnetized as well. The 3340s doesn't have the higer fidelity in sync as some of the later teac/tascam models do. Hey, at least you have sync. I lived with it for many years. go have some fun recording.
Best,
Rick