Bleed hydraulic brakes. Disconnect hose from bottom of MC, connect bottle with air hose to this hose. Attach bleed hoses and overflow bottles to both brake calibers. Apply air pressure to hose at bottom of MC, bleed air @ each brake caliper. Reconnect hose to bottom of MC, fill MC through the vent hole. Connect pressure bottle to left caliber, apply pressure, bleed air out of MC through vent port. Install grease zerk on vent hole, venting will take place out the top of the MC through the washer, since there is no seal on the OD of this washer under the C-clip (o-ring on the ID of the washer).
