Have you adjusted the caliper itself? What LT 1000? 917.xxxxxx

It's a 917.273398. I had looked for help on the Internet without success, but now throwing in the word caliper led me to a YouTube video that seems to explain the whole system very well. I had already ordered brake pads so when those arrive I'll give it a try. Thank you.

Here's the parts list.

That lever pushes on the pins which press the brake pad into the disc. Provided the caliper isn't seized or the pads worn, turning nut number 23 a turn tighter may give you some headway.

Here's a blowup.

It's shameful that a man doesn't know about that magic nut until he's 67 years old. One turn of the No. 23 and I have brakes, and the mower doesn't roll down a modestly inclined driveway with the parking brake set. When the brake pads arrive I'll get it all smoothed out. Thank you so much for your help.