When my B2 Piston broke I had other forward gears that worked.

You do not have to replace the Plastic Valve/s on the Valve Cover unless you want to. They are supposed to only control the EGR.
The exception is that if they become a Vacuum Leak the Leak can have an effect on the Shifting.

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84 300D, 82 Volvo 244Gl Diesel

Do the simple thing first......check the transmission fluid. You would be surprised what low fluid levels, burnt fluid, or the wrong type of fluid can cause.

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2012 Mercedes ML350 Bluetec 102K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 238K (mine)
1998 Volvo S70 T5 Turbo 211K (kids)
1994 Ford F150 4WD 246K (firewood hauler)
1983 Mercedes 300D 384K (diesel commuter)

Checked the transmission fluid... levels are fine and the fluid is still clear read with no noticable burned smell to it... any other suggestions?

could be the B2 piston or the B2 band. Sorry to hear that.

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'85 300D Cal 280,000 miles
'14 GLK 350 60000 miles

If it's an original transmission with 230k miles, it might be about due. I replaced my original transmission at about 225k miles with a reman, and I just replaced the reman again at 578k miles.

I suspect the previous owners of my car were a little "casual" about maintenance, the transmission wasn't quite right when I bought the car with less than 200k miles. I was pretty good about servicing the replacement and it lasted 350k miles before it started acting up. A couple of weeks ago, the shifts were a little off and adjusting the cable didn't change anything. I had my indy take a look and the fluid looked horrible so I ordered another torque converter and transmission. It's much better, hopefully I'm good for another 350k miles.

Manual conversion

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.