Fortunately, the SolrMarc import tool comes with some scripts to help with debugging – they are found in the import/bin folder under your VuFind installation. They are:
indextest – dump results of indexing to screen
indextest2 – same as indextest, but with extra details extracted from Solr schema
To run them, first make sure they are executable…
chmod +x /usr/local/vufind/import/bin/indextest*
Now you can run either tool like this:
bin/indextest import.properties /path/to/your/marc/file.mrc
(obviously, replace /usr/local/vufind with your own VuFind path if necessary… and replace indextest/indextest2 with indextest.bat and indextest2.bat if running under Windows).
I am also copying this message to the solrmarc-tech list, since you may get some additional advice from there in case this answer is not enough….