Does anyone know how to make elevator tracks not decouple carts and cause them to leave behind carts linked to them? I want to get a small train of a normal cart and a chest cart or two in and out of my mine, and this is the last issue I need to solve. Everything else is working except this...
Getting your linked carts up the elevator without them delinking is... difficult, if not impossible (elevator tracks are a bit funky), so letting them decouple and then recoupling them afterward (with a Coupler Track) is the closest you're going to get.
As for the issue about not all of the carts actually making it up to the elevator, my first thought was Control Tracks. I'm not sure if they're still called that, but they're the ones that gradually accelerate carts in one direction, speeding them up if it's moving in the right direction and slowing them down if it's going the wrong way. You can flip them around with a crowbar, and they'll also flip when given a redstone signal.
So, in your situation, I'd place a few control tracks immediately above and below the elevator and wrench them so they point "downwards" when unpowered (that is, the ones at the bottom should point away from the elevator, and the ones at the top should point toward it, so that a cart placed at the bottom will be pushed straight up the elevator), a coupler track just after those, and then the detector track from earlier just after the coupler at the top. Then, hook the output of the NOT gate that's powering the elevator up to both sets of control tracks. This way, the control tracks will push carts up the elevator by default, but will flip around whenever one comes in from the top.
Also, when a cart comes off the top of your elevator, does it first go up a sloped track before rolling onto whatever horizontal tracks you may have up there? If so, try removing that slope and having the carts go directly off onto horizontal track. With the way the elevator tracks are coded, I *think* that works better. It'll certainly help keep carts from getting stuck at the top.
Has anyone tried using the Tanks from the OpenBlocks mod? I made some and filled them with liquid xp with a fluiduct, but I can't right click them to extract XP like you are supposed to. I also tried using an XP bottler and XP shower from the mod but they didn't seem to do anything. It seems like it is impossible to extract XP from them. Anyone have any ideas?
If your OpenBlocks tanks are filled with OpenBlocks' own version of liquid XP (i.e. that collected by vacuum hoppers and the XP drain grate thingy whose name I've forgotten), it should work fine, as long as there's enough XP in the tank to give you another level. Other mods' versions of liquid XP will not work that way.
For MFR mob essence (produced by that mod's grinder and sewer), you can place a bucket of the stuff in the world (manually or with something like a Buildcraft floodgate) and drink it through an MFR Straw, or pipe it into an MFR Auto-Enchanter along with some glass bottles to get Bottles o' Enchanting, which you can throw against a wall to get the XP out.
EnderIO has its own variant on liquid XP, but if you have OpenBlocks installed, it should just use the OpenBlocks version. Try piping it into an Experience Obelisk and see if that works.
There's also a mod called Liquid XP that Immibis wrote a long time ago, though if you were using that, I think you'd know it. I've no idea if it's been updated recently, anyway.
Chromaticraft has yet another take on liquid XP, but it's called Liquid Chroma, so I doubt you'd get it confused with anything else.