Yep, Victa has never built a ride-on. Rover used to - maybe grumpy is thinking of Masport, or another local 'rebrander' of ride-ons - there have been a few.
The earliest 1970's Victa ride-ons, of which the 8-34E is one, all seem to have been 'MTD Yardman' models.
But it's damn near impossible to cross-reference the Victa model with the MTD model number, without both the MTD Model and Serial numbers - both are required, to search on the MTD Manuals website.
There was probably once a sticker with these details under the seat, but so far ODK members haven't had any luck finding an intact one.
It's not surprising that Victa dealers can't find any parts info, on a machine that's pushing 40 years old, really. Very few of them have been in the game that long! The US situation isn't much better, for these old machines.
In past threads, the closest MTD manual/parts list grumpy has come up with, is that for the MTD 133-480 (pull start) and 133-485 (electric start). These are 34" cut models from the right era, but use a 4 speed gearbox, not 5 as for the Victa.
However, the diagram for the brake parts is identical, and uses the same key numbers, as the one above.
It's downloadable [3.6MB PDF] from
http://manuals.mtdproducts.com/mtd/DocGetter?doc=770-4147.pdfHave look, and see if you can work out what bits you might be missing. This is a very basic mechanical caliper, which just uses the main driven sprocket as the brake disc.