There is another thread on this issue here:
I removed those pins that hold the slide out OUT and have never had any trouble with it sliding back in by accident. Perhaps on unlevel ground it might be an issue but we've spent probably 100 nights in it and it hasn't been.
The threaded rods that hold the slide closed for travel didn't pass through the original holes so they had been ground out (by the P.O.) to accommodate the new positions. I bought mine in a repo auction and it appears it was rarely used, but when it was they didn't know how so did lots of damage.
As in the thread above, the 228D has a potential problem with the rear bed pulling on the very short box where the furnace is. When the bed is weighted with people it pulls out on that box and I would bet that is the alignment problem, not the slide going out of alignment.
On mine I put a metal tie-plate to firmly attach that box to the frame. If you pull the flat rubber piece that is attached to the short box, and brushes up against the slide, you see a bar of aluminum that butts up against the frame.
I pulled the bed out, forced the bed up by pushing a canoe paddle up under the bed. This forced that aluminum piece to be closer to the frame, and I used self-tapping screws to join the frame and aluminum piece to stop it from pulling away when the bed is weighted. Seems to have worked for me.