R help - Jul 2012 - PCM() non-convergence problem: how to get diagnostics?

I am attempting to fit a partial credit model using the PCM() function in eRm.
My data set comprises 88 items in 43 individuals with possible scores 0,1,2,3.

Attempting either a PCM or RSM model fit simply hangs - no error messages but no
return to command prompt and a continuously spinning "work in
progress" indicator.

The scores are from an instrument whose relevant psychometrics (e.g
unidimensionality) have been established in other clinical populations: I'm
studying a new disease group. I strongly suspect the problem relates to
undesirable properties of the dataset: a significant missing data rate (about
20%) and a rather uneven distribution amongst the possible scores with relative
paucity of 1 and 2 responses. I have in fact already deleted one item because of
an "The following items do not have responses on each category"
warning.

I was trying to generate some diagnostics to get a better idea of what the
problem(s) are, and/or adjust default parameters used in the nlm call to see if
this helped achieve convergence. Setting options(warn=1) doesn't appear to
help and am unclear how set flags such as print.level for the nlm call?

Thanks for any help

Rob Forsyth