The durability of the Aicore's was from the Coroplast material it was made from And tthey were quite durable surviving horrendous crashes, This however was at a price and that was weight, The performance loss compared to common trainers of the time was reduced somewhat by using a higher aspect ratio wing (wingspan divided by wing chord).
The airplane was not an arf but instead a kit, Just a box of flat preprinted sheets that you folded at the lines and glued with plastic solvent.
The engine, fuel tank, battery, receiver and three fuselage servo's were all mounted to a giant chunk of plywood that would slide out in plastic channels as you noted. To remove the tray rudder and elevator clevis' were removedas well as the nosewheel that you mentioned. There was a small screw on each side just at or beside the engne that secured to ply tray to the plastic rails. Now it was not unknown for some folks to simply glue the ply permanently to the rails. If that's the case you are SOL and to gain access you will have to fabricate various access panels.
The airplane is a nice flyer and I did train a few with them but it will use more runway than others and it will snap roll off the ground if forced off too soon. Do not be tempted to use an oversized engine (anything over .46) as it will turn into a flying monstrosity, very unpleasant.
Balance it no further aft than quarter chord or the results will agine be very unpleasant. .
John
