Hello,
I own a 10006 but I think the brakes on the 13006 work the same way.
On your 13006 the brake pads should be inside the rear axle. You have to take the axle funnels off on each side. Inside you can see the brake drums, which you should be able to pull right off the shaft. The pads are located behind the drum.
There are two sets of pads on your tractor. The pads mounted to the gearbox are the ones for the parking brake and the outer ones inside the axle funnels are for the foot brake.
Hope I could help
By the way pictures of your tractor are welcome
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