Once the centering spring is removed, you just simply lift the centering plate off and you'll see the pintle arms that control the pump shafts. Now you can see the problem, the wear on those two centering spools bolted on the pintle arms. I'm seeing these worn spools more and more on newer model machines. We own an S185 that's just a little over a year old, about 800 hrs on it, and these spools have been replaced twice. Once this wear occurs, the pintle arm isn't being held in neutral position and will cause the machine to creep.
The spools have a 3/8" hex key hole in the top of them, and are fastened to the pintle arms by a hex head bolt from underneath. And there's not enough room to get even a short socket under the pintle arm to grab head of bolt. Additionally, the bolt head is in a recess, can't even grip enough of the bolt head with the open end of a wrench. More brilliant Bobcat design.
I have a 9/16" S-K wrench that has just enough protrusion on box end of wrench to grip just enough of the bolt head to pop spool loose with allen head socket on spool. All you have to do is break the spool loose, give it a half turn to clean metal, and lock it down. But I remove the spool and install a split ring lock washer on the bolt for a spacer, that makes getting a hold of the bolt head much easier. Here's one of thespools and bolt.
Turn both spools on the two pintle arms around to fresh metal. And while your in there, be sure and check the bolt that locks pintle arm to pump shaft, that bolt needs to be tight.
The steel bars bolted to the centering plate are going to be worn as well, simply remove the fastening bolts of the bars, flip the bars around, and bolt them back on. The bolt holes on right bar are round, the holes for the left bar are slotted. Lock down the bolts in the right bar, but leave the ones in the slotted holes for left bar loose to make adjustment.