I've tried load("simp.lisp") using both Maxima 5.26 + GCL and a fairly up to date Maxima built using CCL. After loading
simp.lisp, the testsuite gives plenty of errors--rtest5 gives an error break, for example.
Sometimes it's convenient to make a small change to a file, load it, and run the testsuite. For simp.lisp, it's not so easy :(
--bw