In some cases, you may need to correlate crawl times with Solr issues. Fortunately, the Manifold CF page has a history report of previous crawls. 

1. On the Solr box, go to http://SolrMachineName:7602/mcf-crawler-ui/.
2. Log in with admin/admin.
3. On the left side, select Simple History under History Reports.
4. In the connection selector, choose your core name(your core can be identified in your solr node status page in the workarea settings).
5. Set the time period you wish to see crawls for.
6. Click continue. 
7. In the report, you will see "Activities" in the top right. Select job start and job end. Make sure only those two options are highlighted, then press go.