Normally, when the lights come on and codes are set, the pump has stopped working. If yours is just leaking, you might be able to just change the o-ring, especially if the pump motor is dry. If the solenoid block is leaking, it would be a different story.
The problem I came across was the electric motor portion of the pump stopped working. It seemed to have taken a brake fluid bath from a leaking o-ring. Before removal I smacked it with something and it began to work, as you know this is common with electric motors. Of course I wasn't going to let this car back on the road without replacing the troubled motor. The OP found the leak before the motor failed but it seems jhknight is experiencing a failure. I intend to add some pics of the pump I replaced later on.
The brake accumulator booster assembly just started leaking yesterday, no brake warning light yet. 2002 Prius with 163,000 miles. I would like to replace with a used unit and have located a few on eBay - comes with 6 month warranty. Avi - Can you recommend an independent repair shop in the Chicago area who can perform this repair? Thanks much for your sharing of wisdom and knowledge on this forum.
Update - I bought a brake booster accumulator assembly from a salvage yard in Oregon, supposedly only 50K miles, no rust, $145.00. Found a local repair shop that has the brake bleeding scanner to install the part for $520.00. Much cheaper than dealer price. Part has been on the car for a week, no problems so far. Owning a high mileage used Prius is not for the faint of heart. Lots of high tech parts that potentially could cost a lot of money to fix.