a c-500 ys80 w/mico-lok master cyl holding residual press in brake system giving operator fits when unloading trailer in street trying to shuttle back=forth. just enough press to drag brakes slightly and energize inching cyl. i have been replacing master every 2 yrs or so. when stuck,the plunger is topped out in cyl+there is the corect amount of free play in push rod. crack the bleeder +bing alls well. any one experience the same? mike aloris