1960 bug won't stay in 2nd gear

[RobE30]

Like the title says, my 60 bug won't stay in 2nd gear unless I'm accelerating. If I let off the gas, it creeps out of gear. All other gears function as expected. It shifts smoothly, no issues with that, no noises. I replaced the shifter coupler.
As far as I can tell, it's the original 60 trans.

I know it's hard to diagnose a mechanical issue via computer but I feel like you guys have dealt with quite a few issues and could help.

Thanks

[daveblank]

Are the mounts good?

[RobE30]

I was told the front mount is tired. I have a new mount but have not installed it.
Probably a good place to start

[Ojai63dbl]

transition mounts can do this as the engine will twist on accel and decel. you can tell be looking at tailpipes or engine when reving, it will flex. You can also see the gear shift jump to left (I think) on decel. and back to right on accel. It is picking up twisting of transmission with a broken mount (rubber mount). Mounts are fairly easy to replace (I like dropping tranny, others like push/pulling it back to get front mount in)

the other cause of this issue (that I have had) is a bad synchronizer in transmission (they are brass and wear out)