I recently was given a Saeco mould because the owner could not find handles for it. It is a Saeco #397 148 gr. wadcutter mould with winged sprue plate and different handle attachments. I made a handle to fit and cast up a few slugs and it works great. The only drawback is the sprue plate and it's lack of a stop pin. Before I change the plate and add a stop pin, am I ruining a great treasure. Will the next man who see's it tell me I runined a $100.00 mould. Are these rare and collectible or can I just use it.

Sounds like one of a casting machine. They are set up different. I don't think you will hurt it by modifying the sprue plate. Or you could make or have a new sprue plate made.