Verify that MFM controller WD1002A-WX1 works

I recently purchased a WD1002A-WX1 off of ebay. I am trying to make it work with an ST-251. If I use debug and type '-g=c800:5', I get 'divide overflow'. Am I using the the right debug command?

Hardware:
WD1002A-WX1 ROM: 62-000043-010
IBM XT
MSDOS 3.3
Seagate ST-251

Jumpers on WD1002A-WX1:
s1-1 to 8 - OPEN
W6 - 1-2
W4 - 2-3
W8 - 2-3
W7 - 1-2
W3 - CLOSED

Any help would be appreciated.

Just for yucks, while you're in DEBUG, do the following and see what pops up:

D C800:0

The first thing to do is to make certain that there's actually a ROM image there in memory...

Try using SpeedStor. I've found it sometimes works when debug craps out.