Screw won't grip  

RE:

Hello, i think that screw is only for hold in place by building the next steps. There comes 4 more screws from the motor. So it is posible that the next steps seems a little bit difficult to hold the part in place.

You can contact the support they send you a spare part, and yes you can buy the E3 spare part, they send you the newest one, its only the discription that is not actual.

Sorry for bad english, without google transl.

RE: Screw won't grip

Posted by: @clem-3

Hello,
I'm currently assembling the Core One+.I'm having the problem that in step 29 (29. Installing the motor mount right) the M3x6 screw that secures the motor mount won't grip. It just spins freely.
https://help.prusa3d.com/guide/5-corexy-assembly_982276#990374

Is this a problem?
I also can't find a matching replacement part. I have version E4, but in the shop I only find version E3.
Can I safely order that? Thanks!

Is this a problem?
I can't find a matching replacement part. I have version E4, but in the shop I only find version E3. Can I safely order that? Thanks!

"E" means the part was made by Prusa and "R" means the part was self-printed. The number afterwards is the version number of the part. All of the part STL's are available on Printables. If you have a spare printer or have a friend with a printer, you can print these parts yourself. 

RE: Screw won't grip

I think the hole in the motor mount should be slightly undersized so the M3x6 screw forms its own threads. Make sure you are using the right screw hole in the CoreXY plate to hit the correct hole in the right motor mount (see my red circle annotations) once the rectangular tab is aligned properly (see Prusa's yellow rectangle annotations). If you are using the right hole and the screw isn't biting into the plastic of the right motor mount then since this is a kit I would think this should be well within the warranty period. Contact them for a replacement part before ordering one with your own cash.

As mentioned by @etadriver, this screw is mostly to keep the mount in place until the motor is installed. The motor that goes on this mount (Y motor) is the first one installed, so if you really want to get your printer built w/o having to wait for a replacement part to either be shipped or printed, you can probably leave it to the side and wait to hold it in place it at the beginning of the Y belt and motor mounting (step 46 of the same assembly chapter).