Thx, Norm - good to be back
That soil does *appear* to be at least semi-inappropriate, at least for such a pot...if that really is a shallowish 'true' bonsai' pot, that is. I venture to say that the tree (and what it would take to make outstanding from this point!) is above Jo's abilities *for now*, but it is at a great starting point overall, and I do not mean to offend Jo whatsoever (honestly, I promise)...
I see a really good-movement tree with lots of good cut-back points to get some taper going, and all that lurking within the 'mess' of branchings (that tree is way too tall for itself currently!!! but that is *my opinion* so think before acting, Jo, please).
Firstly, it could definitely use a repotting into a pot-size more 'forgiving', like a bit deeper/wider/longer, etc (again, only if truly a shallow pot that is root-restricting) with a good gritty non-soggy-like soil (plenty to learn *there*, LOL!) if a good recovery is to be more-easily done right now. Chances are that some growth is going to die-back, hence new roots will be forming with the regrowths (right?), so repotting ASAP to coincide with such seems, to me, to be appropriate (y'all concur??). I may be assuming too much in the die-back I predict, but it seems inevitable at this point - most elms take a fair bit of 'abuse' before they look like that, IME, so it likely got 'hammered' by drought (lack of better term here) and is gonna do what I almost always have seen elms do after such - leaf-drop and good backbudding of new 'twigs' (so long as roots ain't toast, which is unlikely here, IMO). If the tree had not been dried, it could be worked within that 'tight' pot, but not very much, of course, but again, it lacks good taper and ramification; call it a quickie-tree probably gotten at a good price...a bit more time/effort can make it into a really, really nice tree
So...having said that, I would get a decent slightly deeper/bigger pot and repot it into that, even going so far as to give it a good root-trimming if it is fairly root-bound in there (bet it is!!!). This will let tree get back its vigor and also grow out new growth in a healthy way, and ramify it as it grows out. *If* so desired, it would be a good time to cut it back (do I see a branching at that first curve?!) to get rid of the typical 'S' bend that is non-unique nowadays and work in some new upwards growth and branchings from *that*...call it a start-over with a great base/nebari. I am only suggesting this as now would be a good time, but it is not mandatory by any means (!). It would take 2-3 years to get the tree worked into a great tapered thing from this point, or using what is there its gonna take at least a full season to get the new growth shaped/ramified anyways - assuming that the die-back happens...
At least make sure it is good gritty soil-mix, and work the ramifying of the 'pads' big-time as it will look soooo much better overall as the leaves will stay smaller/tighter and much more in-proportion. Keep it semi-moist, but always more-dry than soggy wet (if that makes sense), and only fert it when it appears to be actively growing; too much fert will make it grow too fast and give you rather long internodes, ruining the ramification (call it overfeeding, I guess). The tree is at a point where you want it going slower rather than faster in essence, IMO - unless it is repotted into bigger pot and reworked, of course
I do hope I am not speaking over your head, Jo - you *do* have a nice tree there, but it is like jumping into deep end of pool only knowing how to tread water if you are only semi-experienced with 'technical' parts of this stuff (you came to good place, fwiw!)... If I seemed to contradict myself, I'm happy to explain/clarify my rambling typing, haha....
HTH,
Alex