Wow, that's about $80 to get the whole front cover when all you need is the little plastic part that is detachable with bare hands.
One fellow on a forum said he just plugged up the hole that part inserts into when the cover is close with a small section of wooden coffee stir stick and it worked. Or a piece of plastic should do ... since the alternative is to buy the entire front cover.
Found second market versions of the front covers that include the part at printerworks.com for about $38.
RM1-2673, Simplex
RM1-2715, Duplex
Cheers