There's nothing wrong with the brakes in the kit, I had to replace them though as they're brass. Because the brakes sit commendably close to the wheel treads, and I'm mounting the brakes onto the etched inner frame, I was concerned about the risk of short circuits through it.
If you're building the kit as designed, they fit into the bogie moulding, which is an insulating lump of resin, so it's not a problem. In fact, most of the problems I've had have been caused by not building the kit as intended!
What you see above is pretty much a direct copy of the brakes in the kit, so that they'd fit the brake rigging and I'd already designed the mounting around the original parts, before thinking of the problems they could cause.