HEY ADAM,
SORRY TO HEAR YOUR TOOLS ARE DYING.
MY FIST MODEL MASTER BRUSH WAS THE GRAY W/ THE BLACK PANELS ON EACH SIDE.
IT CRAPPED OUT AFTER A YEAR OR SO, SO I CALLED TESTORS DIRECT, THINK IT WAS CUSTOMER SERVICE, & THEY SENT ME A NEW ONE FREE!!!!
YOU MIGHT WANT TO GIVE THAT A TRY & TELL THEM YOU'VE BEEN USING THEIR PRODUCT FOR EVER & WOULD IT BE POSSIBLE TO HELP YOU OUT.
ALL THEY CAN SAY IS NO, SO IT CAN'T HURT.