WHILE CLIMBING THRU APRX 400 TO 500 FT AFTER TAKEOFF, THE PLT MADE A SLIGHT RGT TURN WHICH WAS FLWD BY A LEFT BANK. AFTER MOVING THE CONTROL STICK FOR A LEFT BANK, IT JAMMED TO THE LEFT & WAS RESTRICTED IN FORE & AFT MOVEMENT. THE PLT APPLIED FULL RGT RUDDER & ALTERNATED BTN FULL & PARTIAL PWR. THIS PLACED THE ACFT IN A SKID. SUBSEQUENTLY, IT DSCNDD & STRUCK A 60 TO 70 FT PWR LINE, THEN CAME TO REST IN A FIELD. AN EXAM REVEALED THERE WAS A PLASTIC FUEL SAMPLER & A CLOTH PITOT COVER WITH A METAL CLIP IN THE BELLY OF THE FUSELAGE. MARKINGS WERE FND WHICH VERIFIED THE SAMPLER HAD WEDGED BTN THE CONTROL STICK INTERCONNECT TUBE & THE FUSELAGE STRUCTURE. WHEN THE SAMPLER WAS PLACED IN THAT PSN AFTER THE ACDNT, THE CONTOLS WOULD JAM AS DESCRIBED BY THE PLT. AN EXAM FOR PSBL SOURCES OF FOREIGN OBJECTS REVEALED THERE WERE OPENINGS AT BOTH BOOT COVERS FOR THE CONTROL STICKS. BOTH BOOT COVERS WERE DETERIORATED. ALSO, THERE WAS A 2' CUT-OUT WHERE THE UPPER ELEV CONTROL CABLE EXTENDED UPWARD FM THE FLOORBOARD AT THE REAR BULKHEAD.