ALL THIS SOUNDS VERY FAMILIAR
Although mine (1985 = way past half-a-million miles) is not what I would consider dangerously floppy, and would most likely slide right through a "vehicle inspection", it has it's share of problems.
The first time it did this, back in 1998, I about did wet my drawers.
I had 42 used RR-ties (stacked seven across and six high, average wt. = 280 pounds) strapped on the truck-flat, middle of the night and dark as a dungeon, and was just setting into a fairly sharp curve at the approach to a very long steep grade, not going stupidly fast, but still pouring on the coal, with a semi fixing to meet me right in the curve.
I always keep my wheel at it's highest setting and NEVER adjust it down (except when replacing any one of it's now-five, or is it six, windshields; for some reason, having it all the way up interferes with some part of the windshield replacement procedure.)
With absolutely no warning, the wheel dropped plumb to the bottom, just at the point when my front-bumper was about even with the front-bumper of the semi.
That will get one's attention FAST; I did not "almost wipe out" or even come close, but a less composed individual could have easily gotten their neck broke.
I SELDOM ever hoist myself in by the wheel, only resorting to grabbing it when I feel that I am going to fall back out flat on my back.
Since that first episode, it will do it once in a blue moon, sometimes doing it three times in one trip, then maybe not doing it again for more than a year, sort of biding time so that it can better sneak up on you.
It hadn't done it in over a year, then just a couple days ago, I needed my low-to-the-ground cook-and-mechanical-assistant in the driver-seat to operate some in-the-cab function or other, while I observed whatever was taking place at the opposite end of said mechanism, not in the cab.
Needless to say, very feminine-like, she grabs ahold of the steering-wheel and gives it a mighty yank; the wheel immediately drops, she falls backwards out of the cab, I catch her, nobody catches me, and I warp the gravel (sizable number-FIVEs, not little sandy eights).
To cure the "no grab-handles" problem, I am going to fabricate/duplicate the really neat floor-to-dash-board custom-contoured entry-assist handle that I recently saw in a new VOLVO road-tractor that I had the misfortune to be required to drive.
This handle consisted of a contoured to fit length of what looked to be about 3/4-i.d. sch-40 pipe, with a big square flange bolted through the floor, and another bolted to the dash, up high by the windshield.
It had a second handle, of like construction, secured parallel to the seat-back, bolted to floor and rear cab-wall.
I hate a VOLVO truck, but I must say this was the easiest safest to enter truck-cab that I have ever been in.
I intend to fabricate/attach similar handles to both sides of my cab, as my age-challenged worn-out hips/knees father sometimes accompanies me to pure-bred cattle sales, and he just grabs and yanks at anything and everything on his way up into the seat, sometimes with damaging results.
As for the sudden-dropping column, I am either going to install a complete solid unit from either Flaming River or Borgeson, to compliment my Deluxe Borgeson shaft (I have some months ago posted a question whether anyone had already done this, but yielded no response); or, and I am leaning more along this route, I am going to retrofit a column/wheel from a long-nosed big truck, such that my ton-size truck's wheel will closer match the size and nearly parallel to the floor-board configuration of the big truck wheels.
The older big truck columns have genuine steel components and real U-joints; no brittle pot-metal and plastic in them.
I am also soon eliminating the switch-key mechanism from the column and installing the much more truck-like and far simpler to maintain dash-board switch-key, along with a toggle-overidden "push-to-start" button; reason being, the last few winters, on 20* or colder mornings, the key is somewhat sluggish to turn, warning me that most likely that silly impossible to get at actuator-rod is on the verge of catastrophic failure, likely at the most inconvenient time and place.
I am also ditching the column-lock feature, which in reality is just a useless inconvenience; I see nothing wrong with being able to steer when the keys are not in the truck; genuine thieves learned their way around them many years ago.
My steering whee now moves up & down on the left side about 1-2" 's.
! 
