[Scooter916]

Yep Im with derek on this one sounds as though the lever or master cyl is not fully returning and not allowing the system to recuperate.??
Common problem with aftermarket(ebay) levers, Have u changed the lever recently??
remove the lever and under the rubber sleve at the master cyl there is a small spring these fall to bits at the thought of getting wet, This could also prevent full movement of the master cyl piston.
Hope we help ya out.
glyn