Hi
The main thing if you are contemplating changing the Accumulator or the pressure switch is to make sure you have depressured the system first
Take the key out of the ignited don't switch back on till repairs are completed
Next pump the brake pedal 20 times so the pedal is solid with no assistance .
Then when you remove either item expect to get a cerain amount of fluid loss .
After replacment switch the ignion back on and dont touch the pedal until the pump cuts out.
More likely to be the pressure switch.
Good luck Tim