please help me find memory leak

i learned pascal through reversing-engineering other's code; a process
that is crude but mostly effective.  one thing i didn't pick up from
that method, however, was some how-to like debugging.

i've written a game that uses 320x200x256 vga and soundblaster sound.
everything works great, however, the game lets you play in different
"environments", each of which have their own sound library.  when the
user selects a different environment, the current sound library is
dumped and a new one loaded.  also when this happens, the game will not
shut down properly -- it just hangs.  apparently i have a memory leak
somewhere, but have no idea on how to find it.  any assistance greatly
appreciated.  if the environment/sound library does not change, shut
down occurs normally -- i get my prompt back.  however, i think there is

still a leak because running some applications after my game will cause
the msdos prompt to crash and close.

i'm programming under TP7
the sound library i'm using is ethan brodsky's SMIX.
the graphics library i'm using is some obscure thing called SPX by scott