LIGHT-UP NIGHT festivities downtown were marred when an unauthorized polka broke out in the Diamond. Police made more than 140 arrests and confiscated 15 accordions, 7 clarinets, 2 violins, and a double bass. According to a police spokeswoman, authorities suspect that the incident was instigated by the same gang of known troublemakers who were responsible for last Tuesday’s outbreak of synchronized waltzing on the skating rink at PPG Place.