Brakes dragging are common, bad lower bearing will slow things down. 6K is common when staging and 1st speed limiting switches dont agree. This will cause slow travel because VM thinks the carriage is out of free lift. carriage switch gets plastic often, top switch gets bent arm.
what is battery value when lifting? Are the battery cable pins soldered? should be.
Most important, are the cables from drive amp to drive motor discolored or burned....replace befrore they take out drive amp...