Brake light switch???

I had a similar problem. I installed an adjustable push rod from a vendor advertising here (Can.t remember who). It had a rather large heim joint on the pedal end and came with two washers that I presume were meant to straddle the joint. Upon installation, I noticed the rod didn't appear to enter the master cylinder squarely so decided to omit one of the washers. What I didn't notice was the chubby heim joint then rubbed on the side of the brake pedal. The pedal never seemed to return to the same place making adjustment of the stop light switch impossible. I was always using my toe to pull the pedal 'up'. I finally removed the brake pedal and found where the heim joint was rubbing. A little grinding on the pedal and heim joint fixed the problem.