2005 Ford Explorer 2005 Ford Explorer transmission/solenoid

HI
AT 28K miles my car would jerk when put into drive. Ford replaced the solenoid. Having a similar problem now at 58k-car jerks when put in reverse and is having some delay switching gears when accelerating. Mechanic says, transmission fluid smells like buring but is clear, no error messages when computer diagnostics are run and no leaking of fluid. (Told him about the past solenoid issue) He wants to take apart transmission for $650.00 to look for issue? What do you think?

Thanks!