Does it make sense to take apart the CCU in hopes of finding a broken connection somewhere in the circuit board?!

Also, does the CCU from a 300SD fit the SDL - if so, any particular year?

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1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K