I have a Yamaha MG mixer that I recently gave up on.
Great features for the price, but a nightmare to maintain (in my experience). I almost always have a few dead channels.
The problem is the ribbon cable connections, which seem to corrode easily/fequently. Cleaning them requires removing every knob, nut and bolt of every pot and jack on the top. (No wonder repair places double their bench charge for mixers!) Making the situation even more time consuming is that Yamaha doesn't use male connectors on the ribbon cables...just tinned wires inserted into the board-mounted female connectors. So you need good eyesight and steady hands to reinsert them (two things this over-the-hill bifocal wearing coffee addict doesn't have) without bending the wires out of position.
I have a 15 year old PV board that lacks HPF, channel inserts, etc. of modern boards, but has never given me any problems.
Of course, this is just my experience. YMMV, etc.