Do you have a link to that kit? The JST connectors come in a few different series like XH and SH etc. Just want to make sure I would be buying the correct type.
Thanks
I think these would do it:
Edit, I verified the XH 2.54 is correct but I don’t have any SH 1.0 on hand to check… I’m pretty sure it’s correct though.
Thanks for the info and the verification. I appreciate it. I don’t know why they make so many types of JST connectors but there must be a reason. 
I
Like this ones:
https://www.aliexpress.com/item/1005007476835618.html
Found it is much easier to reassemble if you stand behind the lid of the AMS, i.e. from the rear. Your hand fits into the gap much more easily and you can see what you’re doing at the same time.
Prior to someone identifying the connectors with certainty (and because most of the likely male JST connectors I found were intended for surface-mount), I just cut the 2-wire power cable and the 5-wire RS485 cable and soldered in 22-inches of additional length. (That seems like a lot, but it’s great as I can lay the entire tray outside and next to the AMS housing when I connect the cables to the back of the AMS completely unimpede.) The AMS ribbon cables are #28, so I got a 5-ft ,6-wire #26 ribbon cable for about $6 from Amazon. Arrived the next day, quick soldering, and done. [FYI, BL support severely warned about violating the AMS warranty, but it had expired anyway.]
I was thinking the exact same thing about the longer cables or adding extensions.
BUT
It would probably make life 1000% easier if they made the bottom of the AMS removable. You would then have access to the tubes, first stage feeder screws, internal hub and all the parts within without having to remove the the wiring to start with.
Is it #28 or #26 cable? (I am unfamiliar with these - sorry.) You mentioned both, so I wanted to do the same thing you did, but want to get the correct piece. Thanks.
I just went thru this again and had to strain my eyes and my 69 yr old fat finger to get them reconnected. I’ve contacted a friend, Cobey Schmidt (Geeks at Large) to see if he sells them… he said no but he might look into making them as he sells lots of parts for stuff.
Finally got round to extending the internal cables on one of my AMS’s
For the tiny 5 pin 1.25mm connector I used the 130mm cables out of this kit
They are pre-crimped with both male and female - so fairly easy to make up an extension cable - just a matter of selecting 5 cables and the correct male and female housings and slotting the cables in. The 1.25mm connectors are tiny - so would recommend getting pre-crimped.
For the 2.54 x 2 connector - I used this kit for the Male plug housing and pre-crimped cable. Finding inline Male housings is quite tricky for the 2.54s - I actually ordered another set which ended up coming with PCB mounted male connectors which are much less useful adaptors and extenders.
https://www.aliexpress.com/item/1005007890925061.html
And this kit for the 2.54 female’s which I had to crimp onto the male cables.
https://www.amazon.co.uk/dp/B082ZLYRRN
Crimping these larger cables is easier - but I would recommend getting the proper tool - the link for my one doesn’t seem to work on Amazon UK.
The extra 130mm is a massive benefit- you can very easily remove the inner part and rotate it sideways or upside down. Will make the same upgrade to my other AMS’s next time I need to take them apart as long as the one I have upgraded proves reliable.
Also at the same time fixed two issues with the AMS.
1 x channel was permanently detecting filament when it wasn’t there - solved this by taking apart the first stage feeder, and horn part, removing the circuit board and cleaning out the sensor micro switch and ball bearing.
Another channel was permanently off and not detecting filament insertion. Tried the same taking apart and cleaning out trick but it didn’t work. So replaced the whole first stage feeder with a spare. Will order just the cone/circuit part as I think that is the problem.
BTT is now selling exactly that. BIQU AMS Upgrades Multi Material Reliability Upgrades for Bambu Lab P1 – Biqu Equipment
They look pretty reasonably priced - a bit longer than they need to be - but certainly preferable to making up your own cables.