By 1990, 4020 & 4021 were adequately handling the OCS duties that 4022 was for the most part a full time resident of Reading and the other two would lay over as needed.
In June 1990, 4022 was brought out of winter hibernation and was started up for the first time that year. 4020 gets its windshields washed prior to departing with an OCS and 4022 would go back inside the passenger car shop.
Photographer