Hello Mike,
The lug going from the points through the side of the distributor then to the condensor and coil, must be insulated where it passes through the distributor. Often times the plastic insulators have degraded and cause a short circuit. The 7mm lug should have an insulator on both sides of the distributor wall and a insulating sleeve as it passes through the distributor wall.
If you contact a Bosch outlet they may be able to order any parts you may need. Here is a breakdown and a Bosch number which may help.
Download Attachment: distrib.jpg69.54 KB
Also make sure the "fork" wire end of the ignition points has not rotated close to the breaker plate, or a short may result.
If these are OK my next guess would be the condensor.
Joe Alexander
Blacklick, Ohio