Hi Alex, and a big warm welcome to the forum, it's great to have you aboard! yay
If you check out the thread "Victa Imperial Identification" in this topic, you will see that your Scotty could be a composite machine made in New Zealand by Morrison mowers that was badge- engineered as Scott Bonnar.

For identification, the Model 45 Scotty is the machine in my avatar, and you can also have a look at if you wish, at the thread "Scott Bonnar Model 45 Restored" in the "Old Mower Pics" topic on this forum.

Bruce has uploaded a parts list and manual for the "Imperial" in the Parts and Manuals area which you can access after subscription.
To subscribe, click on "My Stuff" on the top tool-bar, scroll down to subscriptions and follow the instructions.
You may need this manual to help sort your slipping belt problem.
PS..My thoughts are that the V-belt may need replacing! wink
cheers2

Please do not PM me asking for support. Please post your questions in the appropriate forums, as the replies it may receive may help all members, not just the individual member.
Kindest Regards, Darryl grin