I have a Pioneer CLD-D504 that has a tray that won't stay open. It seems to continue trying to open for a moment , then retracts. The Cam Plate doesn't appear to be moving freely, the return spring can't quite pull it into position once the tray is extended. If I manually move the Cam Plate over everything works fine, the tray stays open. I have taken the Cam Gear out and the MB-SW Lever is fine. To replace the cam gear I lined up the pin on the underside of the Cam Gear so it went into the channel on the Clamp Cam. Then rotated it counter clockwise a short distance till the first gear lined up with the mark and the channel for the pin on the Cam Plate was horizontal to the front. Is that the right procedure?

I noticed doing that, that the Cam Gear has a almost half circle ear on the bottom that sort of clamps the Clamp Cam in place when the tray is open. It looks to me like that is causing the Cam Gear and everything around it to deflect just a little bit and that is binding the Cam plate. Has anyone experienced this?

I put it back together once and omitted rotating the Cam Gear to line up with the mark. It released the clamping pressure on the Clamp Cam and the Cam Plate slid back and forth freely. I didn't put the tray in, I wanted to test it without it. When I powered it on, it seemed like it was caught in a infinite loop trying to open and close so I unplugged it.

I am tempted to shave some off the ear on the Cam Gear so it doesn't engage as tightly with the Clamp Cam. Hopefully causing less deflection so the Cam Plate can move freely. Is that a dumb idea?

thanks in advance.

There are three switches underneath the large gear. You have to have those in the proper grove on the bottom side large gear. If you don't get that correct it will never work. If the plate on top of the gear is not sliding properly then the metal over the top of it would usually be bend down keeping it from moving. I've never had to take one of these apart to repair. Either someone really messed this up or you should have wrote before you took it apart.

I bought the player a long time ago. It worked, then I didn't use it for awhile. When I went to use it again the tray started to act up like I describe. I put it aside. I have been messing with it a bit the last day or so.

I am almost certain I have the Cam Gear in place how it is supposed be. That is to say I am pretty careful when I am taking things apart to notice how they were. I have it back together and it works like it did before. Tray won't stay open, keeps trying for a moment and then closes.

I commented here because I am back to square one.

the plate looks like it should, it's flat, with the appropriate raised spots to reduce friction. When I took the Cam Gear out the first time I lifted it strait up, tension on the Clamp Cam was relived. I heard it and saw some deflection I saw earlier dissipate. When I placed the Cam Gear back in and rotated counter clockwise, probably less than a quarter, everything up top was where is was before. The tension released when I took it out, I picture being about the same amount and the Cam Plate slides like it did before. In terms of friction, it has the same amount of stiffness. If I help it out at the very end, when the spring should be pulling it over, the tray stays open.

What I was referring to is there are arms on the bottom side of the cam gear that need to be placed in the correct grove on the bottom side of the cam gear that go to the switches on the bottom of the mechanical assembly. These have to be correct or it won't work properly. You cannot see these until you remove the cam gear and look down in the mechanism.

Go to around 5-8 minutes in this video to see how the gear placement works: https://www.youtube.com/watch?v=FIMBrbRPRro (it is for the single-sided S104, but the loading gears are all the same)

There may be some other switch telling it that there's pressure against the door. And always check the loading belt on these players...

Awesome! Thanks for the link to the video. It confirmed I have indeed been reassembling it correctly. As it turns out, the plastic housing on the back of the unit that allows the laser carriage to get to the other side of the disk is to blame. Well kinda, that piece is held on by 2 screws and 2 small tab style clips. The tip of one of the tab style clips broke at some point and it ended up coated in grease stuck to the clamp cam, the plastic carriage that raises and lowers the laser assembly. Where it was stuck was holding the carriage from going all the way forward, it was being held back by nearly 1/8". When the cam gear would come to its final position when the tray was open it was binding on the clamp cam, the deflection was preventing the cam plate from moving over all the way.

Working great now thanks for the help guys.