Yes you need that part for a number of reasons including but not limited to keeping light out, preventing dust from getting in and spreading the developing solution. A plethora of this model of camera can be found on eBay for under $20.00 including shipping. There is something special about owning a Polaroid and watching the film develop in front of your eyes that the digital camera just can't replace. Since Polaroid no longer supports this model of camera. The most economical and feasible solution here is replacement of the whole camera with a like model. This will allow you to continue to own and operate a Polaroid and have some spare parts back for future repairs.