As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
"B" AUTOPILOT VERTICAL SPEED FUNCTION STICKS AND WILL NOT ADJUST CLIMB RATE EITHER UP OR DOWN. "A" AUTOPILOT WORKS GOOD "B" AUTOPILOT WORKS IN OTHER MODES OF CLIMB AND DESCENT. ACFT GROUNDED. PLANNING RECOMMENDED MCP PART CHANGE PRECAUTIONARY. REPLACED MCP IAW AMM REF 22-11-34-000-801/22-11-34-400-801. PERFORMED MODE CONTROL PANEL INSTALLATION TEST IAW AMM TASK 22-11-34-740-801, TEST PASSED.