What's going on with my AG-1980? Compared with JVC V10U
 

I've been testing my two decks: a Panasonic AG-1980 and a JVC V10U.
When playing one particular tape, the AG-1980 tends to give me lots of white flashes at the top of the frame, and occasional full-frame noisy glitches (is this the TBC freaking out?)

See these video samples below for comparison (this tape is SP speed.)
V10U sample: https://youtu.be/dx4wi6KL4vc
AG-1980 sample: https://youtu.be/uwlxMZolD9U
Side by Side comparison: https://youtu.be/mZnT2xV783k

Any suggestions on why my AG-1980 behaves like this, while the V10U does not?