GE gas turbines from the era following the Northeast Blackout of 1965 had marginally powered Cummins diesel starting engines. They can be replaced with engines originally used in heavy-duty construction industry applications. The new Cummins engines (with 903 blocks) can be adapted to gas turbine applications to provide more power and reliability. Also, spare parts are readily available, unlike their predecessors.
Also, at the same time, the jaw clutch can be replaced with the SSS brand, which has been proven many times over to be far more reliable and durable for frequent starts of the gas turbine.