What's the grub screw for that's labelled 'do not touch' on the Redcat 51 v3 WIFD? Because it fell out on arrival!

[SiD the Turtle]

As the title really, lovely new Redcat 51 with the new WIFD focuser arrived today, on getting it out of the box there was a grub screw loose in the package. Upon checking, it's one of these circled in purple:

The focuser seems fine so far, but wanted to check before I break something by putting it back in!

[saac]

I'm pretty sure that these are generally for setting the float of the bearing surfaces, set up a the factory.  I may well be wrong so stand by to be corrected. 

Jim 

[vlaiv]

To me it looks like one of screws that holds focuser attached to the OTA, but I'm not sure (and that sort of seems logical as you need such screws but they are not listed on diagram).

[Carbon Brush]

Never had hold of this particular focusser. But I'm thinking along the lines of @saac.
The blue & red screws keep the pinion in the correct place for mesh in the rack.
The green screw presumably retains the right hand knob.
The purple screws hold the main shaft (gently) pushed against the opposite side of the shaft bore.
This could be proven (or disproved) by taking the mechanism off using the blue screws  and looking inside.

If I'm right IF IF. After reassembly, bit of screw locking on the purple screws might be called for.
Not a 'hold for ever - drill out' loctite. Anything a bit sticky to stiffen the thread.

Of coure I may completely wrong. Free advice is worth what you pay and all that.

The definitive answer should of course come from the retailer after the long weekend.

[SiD the Turtle]

Thanks all. Seeing as it's brand new and very expensive, I've decided not to mess with it until the retailer responds!

Will post back here when I know more.

[SiD the Turtle]

Retailer and William Optics both told me to simply screw it back in until there was resistance, but not overtighten. I did want to ask WO exactly what it's for after a slightly vague answer, but with the earthquake since, I'm not going to pester them.

The focuser seems fine, but as we have this infinity cloud over the UK right now, not had a chance for first light yet.