Gorgeous boy!
The general rule for preventing hair breakage is: Never brush dry or dirty hair.
In a perfect Show Yorkie world, they would be oiled & wrapped to prevent hair breakage...
Mine are all in shorter hair styles, so I only brush them after their bath, once their hair is clean. For me, it's all about low maintenance now loll.
I always line brush by lifting their leg hair & brushing downwards in layers. This is esp helpful if they have a lot of hair or are prone to tangling....but I don't think Oscar has that prob, he's got beautiful shiny silky hair....what color & size Madan pin brush are you using? If it's not the regular sized soft, maybe Oscar needs the soft cushioned one?