Fuji FP100-C in ISO 75

[LandGuy]

Well, this is my first post here of relevance so here goes.
I have a automatic 100 polaroid. I had some packfilm that polaroid made from two years ago (667 and 669). The 667 is ISO 3000 and the 669 is ISO 80. I finally ran out of polaroid-made packfilm. So I went to the (very far away) store to get some fuji FP-100C ISO 100. The Model 100 only supports ISO 75 (worked with ISO 80 just fine), 150, 300, and 3000. I just broke open the film yesterday. As all of you probably know, the FP-100C is the only thing that is closest to 669. But the shots I am taking are way over exposed. On either ISO 75 or ISO 150. Well its basically completely dark brown (the frame). Their are two settings on the camera. One for BRIGHT SUN ONLY and the other for DULL DAY OR WITH FLASH. I do not have any bulbs unfortunately.
Interestingly, the camera had been working fine for all my Polaroid 667 film that was in it previously. Now the shutter will only open for the time the exposure button is pressed. Its almost like its in bulb mode but the camera is completely automatic. The sensor worked fine with the previous film. Does anybody have any ideas?

P.S- I also have a completely manual 180 that the film works in just fine.

 

[LandGuy]

Im stupid forgive me. Presumably you must hold the shutter down untill you here the shutter close again

 

[ethansmith50]

I like your post. but can you tell me how to set a ISO in normal digital camera. because I fine so much but I never see any option for ISO change.

 

[malkav41]

ethansmith50- Not to be a jerk or anything like that, but you need to ask your question in the digital discussion area, as this is for the discussion of film. Thanks!