From September 11, 1976, to January 1, 1977, service was replaced with buses at night to allow installation of new lighting and electrical equipment in the Huntington Avenue subway. On January 1, all peak and midday service was cut to Heath Street as winter weather caused a car shortage; buses designated route 39 ran between Arborway and Copley. This ended on March 19; regular Heath Street turns were extended to North Station from then to June 18, 1977. Route 39 buses again replaced weekday service past Heath Street from June 18 to September 9 due to track work on Centre Street. Continued streetcar shortages and delays with the new Boeing LRVs caused weekday service to be replaced with buses past Heath Street on October 17, 1977. Service to Arborway resumed in stages, with full service restored on December 31, 1978. The new LRVs were first used on the line for Northeastern short turns on January 16, 1978; these were extended to Heath Street on April 24.