Landing Gear

[Goat150]

HELP,
Can any one tell me if they have ever had the trouble with just the two little gear doors not opening so the gear can retrack !!
This just started out of the blue, With the plane on the ground and the master switch off I can pump the doors down as normal.
Then turn the master switch on and the door close as normal
But on take-off when I push the gear switch up to retract the gear
the big claim doors open but not the two small gears don't. I can tell the mechanic doesn't know what he doing, He said the power pac
was bad , but when I had him check main HYD pressure it's fine,
and the pressure at the door cylinders are at spec to. So I can't see the Power Pack being bad.
Can any one HELP

Mark 740-988-9605
740-710-1967 mobile