In investigating the search options a few days ago, it would appear that I inadvertently set the seach type to MySQL "Full Text Search". The default minimum word size for this search engine is 4 letters so that XLR, JBL etc. would return null results. I cannot change this word size since it must be done by a database administrator. Therefore, I have set it back to the vbulletin search type so that three letter searches are possible again. For example, a search for "XLR" returns dozens of relevant posts.