Unless the mortgage loan is transferable and the lender accepts you as a new creditor AND your brother agrees to the transfer, it isn't going to happen.
Since your brother is not the sole owner, he cannot sell the property in whole without your agreement. At most he can sell his 1%. I suspect you won't find any buyers willing to buy 1% of your property.
If the mortgage has been paid regularly, the bank is not likely to entertain a short sale deal.
Not having pay stubs is not a death knell to obtaining a mortgage loan. There are other ways to prove your income. If you can actually qualify for the loan (income to debt ratio), you need to speak with a mortgage lender to see if they will finance you. If your brother is not willing to relinquish his 1%, you are really stuck not being able to do much.

