me262 & darkzero
But, there are acctully 3 different senor switchs on the drive. I don't think you have any problem with the switches.
1. On the drive lid. It is optical. It is located at the front and has the red and black wires that run on the top of the lid to the left outer side of the drive and plug in there.
2. Sensor at the front right side under the two wings that is tripped by the the black sliding tray lifter.
3. Senors (2ea) that at also located under the two wings that are tripped by by the right wing as a disc is inserted.
The only time I had to replace a drive top is when a PS3 would eject any disc I put in it after about 60 seconds. I am not sure what caused it , but I had brought a working drive, without the control board for parts and changing the top fixed it. So I don't think you guys need a new top.
When ever I open a drive, I always remove the top, unplug the door sensor (#1) and then manually put the 2 wings outward to engage the tray lifter. Then I test the laser or replace the laser. When it is working, I turn off the PS3 and then remove the test disc and then turn on the PS3 again. I press the eject button to set the drive to the "no disc" position. This is the position that the lid is in when it is removed. There are spring loaded arms and trip devices in the lid that are naturally in the ejected or empty drive location. Put the lid down, and hold it in place by hand and turn put a disc in through the door.
If the disc is pulled in by the drive and the the drive attempts to spin it, but only turns for 1 or 2 seconds and then stops, try ejecting the disc. I f you cannot eject the disc take to top off and again return the tray to the empty or ejected disc position. Try again with the lid. Sometimes it takes 3 or 4 times.
The slide bars have only 2 positions, tray up and tray down. The left side bar is moved a motor under the 2 wings, the right side bar is moved by the left side bar. There is an aluminum lever that you can see from the bottom drive when you remove the bottom metal shell. This lever has a pin on each side that is inserted into the left and right slide bar. The lever then forces the right slide bar forward or backward, keeping it in sync with the left slide bar. If you look at rear area of the each slide bar you will see about 3/4" of the track that this lever rides in. If you see the metal pin attached to the lever then it is not in the proper loation, it must be under each side bar so the they are in sync.
Also, the metal tray the laser and spindle motor reside in has two metal pins that stick into a hosing under the each slide bar. The slide bars then move the pins up or down to lift or lower the metal tray. I had a customer that dropped his PS3 and the force moved the pins on the left side out of position and the tray would not lower any more. If you tray is lowering and lifting, then they should be fine.
I hope this helps. To bad there are no tuts on this drive yet. I will check back later, I have to go to the shop, I am behind on dozens of 360's, PS3's, DS's, PS2's, and a Wii to fix!