I can't help much with the lock other that to ask if you can tap out a
larger hole and use alternate hardware. I have even seen bolts with welded
or epoxied wrenches used for this kind of duty.

However, I got tired of lugging the table on my old Craftsman up and down.
A year or so ago I added simple counterbalance. My machine had a tube
clamp that acted as a safety just below the head of the drill press and I
used this to attach a small pulley (about 1-1/4" wheel - hardware store
quality). Using an available tapped hole in the back of the table, I
attached a standard hardware screw eyelet. I looped and crimped a length
of 3/16" steel cable from this eyelet up to the pulley and let the cable
hang down the back of the machine for sizing. I rounded up a suitably sized
and stiff rubber bungee (the kind with metal hooks on either end). I hooked
one end to a bolt that secured the base to the up-tube. I played with the
cable length until I found a length that more or less nuetralized the weight
of the table; then cut the cable to length, created a loop and secured it
with a crimp. Total investment was around $7-8.

This is not a perfect counterweight but it makes moving the table up and
down MUCH easier. BTW I installed this counter-balance after I installed a
30"x17" auxilary table and fence.