Hello Aquarabbit! Nice to see
another Canuck, I grew up in Vancouver and my wife is from Calgary, but we live in Houston. I believe you are our first from Saskabush, so I'll add a
Geographic Type Board in case you have local type posts.
I understand that your problem is not in making mozz but rather in getting a good curd set.
I also use store bought past & homogenized cow's milk, first 20 batches without CaCl2 and no significant problem getting a
good curd set.
Sorry but I haven't used tablet style rennet, if you search this Forum for "Tablet" you'll get a bunch of threads with other people using it and their experiences (both positive & negative).
Just to check, rennet is very very concentrated stuff, you are diluting in water first right then trickling in then stirring thoroughly for 1 minute max right? If you stir for 2-3 minutes it may already be setting up and you'll destroy the gel.
Some guidelines here.
Hope helps . . . again welcome!