For an older T@B like ours with the glycol tank behind a wood panel in the back corner, I've always found it to be a nuisance having to remove the two extra long square-headed screws for access (Now let's see, was that the smaller or larger square head?).
I've actually had the hardware needed to correct this on hand for a long time, but just now finally getting around to using it. And while T-nuts have been used for this before, I'm using one in a different way combined with a simple thumb-screw for tool-less access..
This is a 2-inch thumb screw with a small head and a built-in collar that replaces any need for a washer. It & the T-nut are 1/4-inch with 20 threads per inch ("1/4x20" in hardware terminology), which photographers will recognize as the standard used for tripods & camera mounts (which is probably why I had it laying around in my collection of fastener bins). I've drilled some holes in the T-nut for securing with tiny wood screws. Although the metal spikes hold it from twisting, screws will avoid losing it to one of the T@b's nowhere lands. (I once found my wife's diamond ring behind the Alde!)
OK, here is what it looks like installed, after carefully aligning & drilling holes through both the panel & wall behind it..
And with the panel removed, you can see the threaded T-nut mounted inside the hole..
And a view of the T-nut installed from inside the cabinet, with 3 tiny wood screws to prevent the T-nut from getting pushed out the back..
And finally, the photo below is just to highlight that while the cover is removed, I can temporarily screw the bolt back into the T-nut to avoid losing it somewhere down below..
With the old screws, I would often either drop them or forget where I set them down. I had also considered using a small hanger bolt screwed into the same wall, with an acorn cap nut screwed on over the panel, but I mostly didn't like the idea of potentially dropping a small nut while trying to get it off/on.
Also, a single thumbscrew seems to do the job just fine. I placed it a bit higher than center, mainly to avoid interference with using the peephole (white rubber cap) to check glycol level.