C172 PLT HAD ALTDEV AND ERRATIC TRACK IN IMC WHILE FLYING THE VOR-B APCH TO F29.

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WHILE FLYING THE VOR-B TO F29; HAD DIFFICULTY MAINTAINING COURSE AFTER XING IAF; WHICH LED TO S-TURNS DOWN THE APCH COURSE. THE VOR INDICATOR SEEMED TO BE SLUGGISH IN ITS INDICATIONS; AND I OVERCORRECTED; AGGRAVATING THE S-TURNS. ALSO; WITH THE DISTR OF TROUBLESHOOTING THE PROB; I BRIEFLY WENT BELOW THE ALT LIMIT FOR THE INITIAL APCH SEGMENT. ATC INFORMED ME OF MY POS ALONG THE WAY; AND THEN VECTORED ME AROUND FOR A SECOND APCH WHEN IT BECAME APPARENT THE FIRST ONE COULD NOT BE COMPLETED. SECOND APCH WAS BETTER AND RESULTED IN UNEVENTFUL LNDG. ALSO CONTRIBUTING WAS EXCESSIVE PRECESSION IN THE DIRECTIONAL GYRO; CAUSING MY ACTUAL COURSE INTERCEPT ANGLES TO BE LARGER THAN WHAT WAS INDICATED. DURING THE TURNS DURING REVECTORING; I KEPT THE DIRECTIONAL GYRO SET TO THE MAGNETIC COMPASS; AND BETTER ANTICIPATED THE VOR INDICATOR RESPONSE. I SHOULD HAVE PICKED UP THE VOR PROB SOONER; ABANDONED THE APCH; AND DONE THE TROUBLESHOOTING ELSEWHERE; RATHER THAN CONTINUING. THIS WAS ALSO MY FIRST SOLO ACTUAL IMC APCH SINCE BEING RECENTLY INST RATED. I INTEND TO GET AS MUCH ACTUAL IMC EXPERIENCE AS POSSIBLE; IN ORDER TO FLY WELL AND SAFELY IN IMC.