I don't like posting these kinds of threads as I can imagine it's a pain in the *youknowwhat* to diagnose a problem based on text and pictures but I'm really about to start pulling my hair out because I'm out of ideas..

Having built 42006 yesterday (took me about 4 hours, yes I'm a pretty slow builder) and testing all the various functions, I immediately stumbled upon a problem. Raising/Lowering of the boom works great, so does opening and closing the claw. Extending the boom does not..

The upper LA is giving me a lot of resistance when using the 'knob' at the back. When I take out the axle and test the gears without the LA connected, everything is smooth. When I plug the axle straight into the LA and test it I get no resistance at all. Once I place the axle back it takes a lot of effort to turn the knob. I'm out of possible troubleshooting idea's and having reviewed all the instructions multiple times I can't seem to find the problem.

I've also compared my spare parts pile with Youtube reviews and the pictorial review here on EB, the only extra spare parts I have are 2 "track pieces", which can't have anything to do with the LA..

The one that's been bugging me.

On the left, with the axle connected to the LA, it works great.

On the right, with the axle in place and using the knob at the back, I get tons of resistance.

I hope it can be fixed without having to disassemble the entire thing.. If someone could point me in the right direction to what I might have missed, that would be great.

From what it looks like, it seemed that some gearing are off...they are NOT in its proper position. You might want to check the area where all the gears are and see if they are off (not pushed in properly or not in the right position thus turning other gears, etc.).

Hope this helps.

Try to leave a tiny little bit of space between 16T LBG gear (seen in a center of 2nd picture) and liftarm on top, as it looks to be compressed a little bit.

Thanks tedson99 and zux, I've looked into your tips.. I've checked the instructions over and over again, closely inspecting the gearbox, and I don't see any gears that are 'off'.

And I agree the 16T LBG gear looks a bit close to the liftarm in the picture, in real life it isn't that bad though. I've tried moving it but it's not so easy without tearing everything apart. Which is what I'll be doing tonight: rebuilding the gearbox. I'm gonna try and keep as much as possible intact (like the base and the boom) so it won't take me another 4 hours to put it back together.

I seem to recall having assembled the boom in such a way that it couldn't move but I don't remember what I had done wrong. I don't think the problem is in your gearing though, I think it was something in the boom.

On the original build I misplaced one of the red axle's when connecting the LA to the boom, therefore locking it tightly in place and now I fear I may have forced it while testing.. I rebuilt the base structure completely but it didn't help at all. Then I rebuilt the boom which did not help either. I'm suspecting the LA itself might be causing the trouble.