The team had to revive a thruster used for roll control whose heaters had failed in 2004. The tubes of the backup thrusters currently in use are getting clogged and may fail this year.
The delicate operation required turning on the failed thruster and flipping a switch to enable its heater and 🤞
All very tricky and risky operations, performed from 23 light-hours away on 1970’s era hardware.
I’m reading it as the 9-month loss of signal being due to construction at the ground station (DSN Canberra), not anything to do with the spacecraft itself.