Loosen the pivot bolt(s?, it's been a while) and the nut for the adjuster. The adjuster is the one with the cog just behind the bolt head that rides in the "rack" on the bracket. Turning the adjustment bolt will move the pump.
It's a clever design that works well provided someone who didn't look first hasn't ruined it.
If the rack has been stripped already about all you can do is use the old pry bar to get it where you want it and tighten down the adjuster nut.