Hi:
I know this is a 10 day post, but the only reason for a 510 to weigh a lot is because somebody 
put weight, like bricks, in the bottom.  Probably weight less than a Stoner.  If I were looking for old candy machine
that would vend for decent price, the 510 would be my choice.
I like them, we a 4-5 still in service until early/mid 90's.  They had been converted from sliding mechs
to electronic mechs.
I have 2 conversion mechs, but no 510 

Gary