Hi Barry, on John's MSA I did it (as per the last picture on the linked page, the bracket at 10.00 o'clock on the pic!) when you pull the Eb crossbar simply slide the bracket and lock it against a bellcrank placed at the end of the bar close to the back apron, works a charm! regards, Bob
Screw lock Barry, A slot the width of the thread is milled out the angle bracket, slid along when the lever is engaged and the knob then tightened, perfect lock to Eb, not unlike the principle of pedal rack quick release leg brackets. ....regards, Bob