Razor MX500/MX650 Rear Band Brake Assembly with Rotor & Spring - 90mm (Silver) Jonway YY50QT-5 2-Stroke Here is the armrest adjustment

Here is the armrest adjustment knob for the ActiveCare Catalina and Drive Medical Titan power chairs

Unfortunately

This brake assembly for Active Care Spitfire 1410 mobility scooter is the perfect replacement for your worn out or damaged brake assembly

This is still the size used on current production (2010) scooters

If you want good looks

Razor MX500/MX650 Rear Band Brake Assembly with Rotor & Spring - 90mm (Silver) Jonway YY50QT-5 2-Stroke Here is the armrest adjustmentRazor OEM rear brake assembly for the MX500 and MX650 electric dirt bikes. Silver painted steel body. Riveted band brake Rotor = 3 1 2" Outside Diameter