Mike,
I found that I had exactly the same problem when I did my Optical Train adjustment the other day. By putting the 2ndry in the correct position meant that I couldn't get full focus with the Toucam.
I fixed it by simply turning the collimation screws 2 full turns which moved the mirror forward about 2mm. It was enough to make the toucam pull focus and have a smidge past focus as well.
Then I just re-collimated with the mirror in the new position. The collimation screws still have a long way to go, so it's not a matter of the mirror cell falling of the end of the screws.