Dacor Pinnacle Raised Cooktop Vent Repair

We inherited a Dacor cooktop when we moved three years ago. Aside from the noise, it seemed to perform adequately until a couple of months ago.
Then, the function of the fan started to suffer. It sounded as though the fan was occilating in speed. Then the response of the system to other touchpad controls became unrealiable. Now, it will not respond at all.
Does anyone have experience with this particular unit? I would like to take a crack at diagnosing it and perhaps fixing it rather than immediately calling an expensive repair guy.
The model is an RV36S.
All thoughts welcome.
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