Although not totally required, you can get a vacuum gauge for about $35 at an autoparts store or from amazon.Or older.
I reached out to SS for some advice on Monday and they haven’t returned my call.
From what I understand I need a vacuum gauge to test the integrity once the seal is changed?
I need a clutch plate regardless
https://www.amazon.com/Actron-CP7830-Hand-Vacuum-Pump/dp/B0009XQUK2/
The shaft seal itself is about $30
The seal is nearing the end of its life for sure and if it leaks it will do a whole lot of motor damage fast