I doubt they can be super glued, they may be able to be soldered, but it's best to purchase a replacement as they can be had off eBay for under $5.

I replaced my midframe and I consistently get 1-2 bars less than my wife's stock iPhone 4. Blue inductor is present. I cleaned the cellular antenna connector wire and socket with alcohol and it still get's 10-15dBm lower. I do know when I replaced the speaker/antenna assembly, 2 of the 4 prongs broke off, but I thought they were for EMI purposes only? I'm thinking the blue anodized finish of my midframe is causing a connection problem, perhaps at the brass tab/screw to the right of the assembly (opposite the connector to the board). I guess I'll replace the GSM antenna assembly next as well as sand off the anodized finish of the frame where the screw is that I was speaking of.

Don't use a toothpick to press them out, you'll damage them. Instead, using a heat gun to soften the glue holding the black plastic blocks above each one, then pry them out using an iPod opening tool. This way, you'll be able to reuse them as well as the screens.

Sounds like your only issue is with the sim. Have you tried a different sim? If not, try focusing your cleaning efforts on the sim socket. I've seen replacement sim sockets sold online, so the removal and repair of one shouldn't be too hard

I had this issue as well. I recently swapped mid frames and glass on my AT&T iPhone 4. I swapped from black to white glass. My new glass came with the sensor "fix" sticker already attached, it didn't have little holes but one large window (the newer design). I replaced the sensor cable and still had the issue. I even saw that they were selling the sensor cable fix stickers online and I replicated it with some electrical tape and stuck it onto the frame of the phone over the sensors, cutting very small holes for the sensors to be restricted as to the amount of light they were putting out. That didn't work either. What DID work, however, was looking at my old frame, and finding a strip of foam running between the two sensors. I removed that strip and placed it on top of 2 strips of tape on the new frame, between the two sensors, to ensure it was thick enough to hit the new glass. It worked like a charm! What it is is light bleeding over from one sensor to the next by reflecting off the front glass into the othe...