LOSS OF ACFT CTL.

Narrative

1) PROBLEM AROSE THROUGH INATTN TO INSTS DURING CLB IN IMC. 2) CONTRIBUTING FACTORS INCLUDED SEVERAL CALLS FROM ATC FOR INFO ON CLOUD BASES; CONFIRMATION OF ALT OF CLOUD BASE; SQUAWK CODE AND REVISION OF ASSIGNED ALT. 3) NUMBERS 1) AND 2) CAUSED AIRPLANE TO BANK L AND DSND SHARPLY. ARTIFICIAL HORIZON 'HUNG UP' AND NO LONGER INDICATED ACTUAL ATTITUDE. THIS WAS DISORIENTING AND CTL WAS TEMPORARILY LOST WHILE PLT STRUGGLED TO INTERPRET RAPIDLY CHANGING ALTIMETER; VSI; AIRSPD AND TURN AND BANK INDICATOR. SEVERAL GYRATIONS OF THE ACFT OCCURRED UNTIL AIRPLANE BROKE OUT OF CLOUDS AND GND REF BECAME AVAILABLE. ONCE OUT OF CLOUDS; I RETURNED VFR TO MHT ARPT. 4) ONCE GYROS WERE 'TUMBLED' ALL SENSE OF ATTITUDE AND DIRECTION WERE LOST. RAPID MOVEMENT OF REMAINING INSTS WAS INITIALLY CONFUSING. 5) INITIAL PANIC PROBABLY CAUSED OVER-CTL AND OVER-REACTION TO UNCERTAIN ATTITUDE. THIS MAY HAVE WORSENED THE SITUATION INITIALLY. AS UNDERSTANDING OF THE SITUATION IMPROVED; CTL AND STABILITY IMPROVED. SEEING THE GND; FAINTLY THROUGH THE CLOUD BASES; GAVE SUFFICIENT REF AND CONFIDENCE TO REGAIN FULL CTL. 6) ATC WAS HELPFUL/PATIENT ONCE THEY KNEW I HAD A PROBLEM. MY PRIMARY MISTAKE WAS LOSING MY INST SCAN AND NOT BEING AWARE THAT I HAD DONE SO UNTIL MY ATTITUDE AND DIRECTION INSTS WERE TUMBLED; AND/OR HUNG-UP. 7) I HAVE SCHEDULED MY ARTIFICIAL HORIZON FOR RE-BUILD/REPLACEMENT THIS MONTH. I BELIEVE THAT CTL COULD HAVE BEEN MAINTAINED HAD THIS INST NOT HUNG-UP.