No mention when instaling the NEW fan, of what to do about the tape that secures the fan to the heat sink. The new fan didn't come with any tape, but the exiting black tape has metal contacts on the underside that appear to line up with metal contacts on the heat sink. I just carefully put the old tape back on the new fan, lining it up with the metal on the heat sink. I hope that was the right thing to do! Works fine. I recommend iStat widget to see your fan's rpm's. Helped me confirm that my old fan was caput (zero rpm's while right was at 2000rpm's) and the new fan reads 2000rpm's same as the right (and I can hear the new fan, but not nearly as loud as the old fan before it stopped altogether).
the technique you describe of putting the front down first, is exactly what I did and it worked well