At least on the 507, the headshell is a standard 5 DIN, so that's easy to replace. You can contact Dynavector's distributor regarding getting an original one, or get a Sumiko headshell, which allows for azimuth setting.
I'm not sure what you refer to as the 'bottom plug'. Do you have a link with a picture?
Best,
iSanchez
I'm not sure what you refer to as the 'bottom plug'. Do you have a link with a picture?
Best,
iSanchez