Dr_Ju_ju

Very simply, and you don't say what type of mount you're asking about (Alt/AZ, Equatorial, manual, motorised etc.), but in general, If everything is properly balanced, then friction of the gears meshing together, due to the weight pushing down. will 'hold' the mount in the same position, but slewing the mount around will obviously move the balance point, and so 'push' the mount to a different position. Note there are additional friction locks on each axis, if you wish to stay in one place, but the target will move out of field of view due to the Earth's rotation etc.

Back to basics.... Does your new laptop have 'standard' usb3 ports and or any usb2 ports ? also do you have any short, good quality , usb cables cables and maybe a good quality external hub ? If you then connect each device singly, and monitor the computers device manager, especially looking for 'un-recognised devices', but also at the same time have system event viewer open & monitor what windows thinks is going on...

If you prefer RDP over VNC (personally I do), why not install xRDP (xrdp by neutrinolabs), you can then just remote desktop into each remote host, whether that be windows or linux based....

They may not be exactly the same, but they are on ebay i.e. https://www.ebay.co.uk/itm/Wiska-10102370-EVSP-12-Vent-Plug-Black-RAL-9005-M12/143939453837

Is the right location set in the EQMod control panel ??, i.e. expand the panel, with the spanner >> icon at the top ....

If you can find the size of the thread (diameter & pitch), then I'm sure one of those industrious chaps north of you (for OZ that is), may well be able to supply something close to what your after e.g. https://www.ebay.co.uk/itm/M8-M10-Steps-Knurled-Thumb-Screws-Aluminium-Handle-Stainless-Steel-Thread-Rod/124161416204 or AliExpress etc....

you also need to ensure that the USB controller devices (Device Manager) are all set, such that the power management, is set that "Allow the computer to turn off this device to save power" is disabled....

Don't forget the drivers for all the hardware.... plate solving software, eqmod ?....

if using external knobs to the Synscan software, then no, there will be no update on the Synscan display....

1.5 mm across the flats ?? I doubt there is one, the smallest I know of is 3mm.....

If the menu doesn't show what you want, it my be worth installing Magic Lantern (Magic Lantern | Home) onto the SD card, as this software 'exposes' more of the in-built functions....

Did you generate the STL files ? if so using what ? If not where did you download them from ? For something as large, and without the hardware that is to be mounted, it can difficult to ensure that everything will fit ok, with enough clearances for all the internal components....

Digikey have them TSL237S-LF ams | Sensors, Transducers | DigiKey

Personally, I'm always suspect of the devices used for charging in vehicles as I've found them over voltage & sometimes the Pi's can get upset.... So instead I use a dc-dc converter e.g. https://www.ebay.co.uk/itm/Better-Waterproof-DC-DC-Converter-12V-Step-Down-to-5V-Car-Power-Supply-Module-3A/133490822065?epid=14036484897 which I wire into the GPIO socket, but also means I can add additional safety components, if required, e.g. fuses, switches etc.

It probably doesn't need a 'split' coupler as that will introduce backlash, I find a straight coupler works fine.

...... and apparently it needs to be enabled, I believe that there is a series of posts on CloudyNights detailing how to enable it, after first setting the date\time.

Yes, to high torque Nema 17's on my EQ5, but driven by an AstroEQ board using TMC driver modules....

From what I can find, your mount doesn't have an RTC, only the CGX does, so if you think it does, what does the manual say ??

IF it was truly 15volts and not something higher, then you may have got away with just frying the input regulator, but as many laptop chargers usually come out nearer to 20volts, I suspect more damage has accrued....

I don't have the mount, so just shooting some ideas.... Having a battery doesn't necessarily show the presence of an RTC, as the battery would also be used for keeping the settings stored in nvram, so does the HC have an RTC chip ? or is it in the mount and only shows up when they are both connected ?? If it's in the HC, Is there an internal link that needs to be set ??

I'm confused, as I work under the impression that the extrusion thickness is taken into consideration by the slicer, which will adjust the amount of material extruded, to cater appropriately, such that parts end up the correct size etc...

Dropping the STL into Tinkercad & PrusaSlicer, shows the wheel size to be 141 x 141 mm is that correct ?, and even though the central hole appears central, the sizing, depending on the slicer you're using, can sometimes 'offset' holes...

Post the STL file & I'll check it out ....

You should be good to go, for me, I've been on 6.5 for a long time with no issues....

What is it you're actually trying to do ?? build something like an AstroEq (Tutorials & FAQ’s (astroeq.co.uk)) or ??