A little clarification...do you have damage in the Master Cylinder housing/brake lever pivot area? Inspect pivot/housing (cast aluminum) or the lever itself is bent or has evidence of scrape marks? Check the little "nib" that is underneath the brake lever pivot area.
If someone disassembled without putting a penny or shim under the lever, the brake switch may be damaged as well. Use the Self Help for tips or the Search tab...typing brake switch lever to find related threads. You should be able to diagnose problem.
The other deal is the switch is easily replaced, but you have to disassemble carefully, there are small parts that can fall out if you don't do this and in a clean area, they can be hard to find crawling around on the shop floor...!