I have always hated the way the fence on my older delta mortiser worked.
It would twist in the wind, was difficult to set precisely.
Well I solved that with 2 mods.
One a simple one, add a wood face, the other, I drilled through and
added 2 small maple blocks inboard, over the cast base, so they don't
bend the crappy table they provide you with.
Now it no longer twists while tightening it, and it glides like you
wouldn't believe, making adjustments cake. The 2 blocks were cut from
one properly sized piece. Thinned to just the right size.
if you have one and are struggling like I was, try it.