C172 PRACTICING IFR APCHS INTO BAF VARIES FROM ATC ASSIGNED ALT AND HEADING.

Narrative

ON BEING VECTORED FOR THE ILS RWY 20 AT BAF BY BRADLEY APCH CTL ON A PRACTICE APCH IN IMC AT MY ASSIGNED ALT OF 3000 FT; I RECEIVED A NAV FLAG ON THE LOC/GS READOUT INST. I INFORMED BRADLEY OF THE FLAG; AND ASKED TO HAVE TIME TO FIGURE OUT THE PROB. BRADLEY TOLD ME TO REMAIN AT 3000 FT AND GAVE ME A HEADING OF 110 DEGS. FOR THE NEXT 5 MINS I TRIED TO FIGURE OUT WHY I WAS GETTING FLAGS ON BOTH NAV AND GS. I WAS UNABLE TO DETERMINE THE SOURCE OF THE DIFFICULTY; SO I SWITCHED TO THE #2 NAV SYS AND REQUESTED THE VOR APCH TO BAF RWY 20. BRADLEY VECTORED ME AROUND; AND THEN CLRED ME FOR THE APCH; WHICH I EXECUTED AND LANDED. DURING THE TIME I WAS INVESTIGATING THE PROB; BOTH MY HEADING AND ALT VARIED CONSIDERABLY. I WAS MORE THAN 300 FT ABOVE AND BELOW THE ASSIGNED 3000 FT ALT; AND MY HEADING VARIED SUBSTANTIALLY. I WAS IN SOLID IMC THE WHOLE TIME. WHILE THE CTLR WAS PATIENT AND HELPFUL; AND I EVENTUALLY (IF SOMEWHAT ERRATICALLY) WORKED MY WAY BACK TO THE ARPT USING THE VOR APCH; I AM RPTING THE UNINTENTIONAL DEV FROM ATC ASSIGNMENTS. I REALIZE NOW THAT I SHOULD HAVE XFERRED SOONER TO THE NAV #2 SYS AND CONCENTRATED MORE ON STABILIZING THE APCH. ALTHOUGH I AM IFR CURRENT; I HAVE SCHEDULED TIME WITH AN INSTRUCTOR TO IMPROVE MY PROFICIENCY IN ACTUAL IMC.