As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING PUSH BACK, WITH PACK 1 ON, SMOKE BEGIN TO ACCUMULATE IN THE COCKPIT. WAS ACCOMPANIED BY AN ELECTRICAL SMELL. SEEMED TO COME FROM FO SIDE. COULD NOT DUPLICATE PRESENCE OF WHITE SMOKE. FOUND NO VISUAL SIGN OF BURNING. NOTICED BURNING SMELL WITH PACK 1 ON. R & R NR 1 ACM IAW AMM 21-51-03. OPS CHECKED GOOD. NO PRESENCE OF BURNING SMELL. OK FOR SERVICE AT THIS TIME