We do not have to many digital counter issues on the boat I fish on, but as a back up there are manual counters are installed.
We had a good friend install the counters because he has done it before and knows his Scotty stuff.
If we have a digital counter go down, we pull the plug out of the lid and set the counter to 0 and continue fishing. Change the digital counter back at the dock.
Here are some photos of the installation a friend installed in the DRs
I'm surprised Scotty doesn't sell a manual counter for the high speed DR. Or an optional back up kit to add a manual counter.
We have not used the manual counters in a while, that is why the numbers are different. We also use the scotty thick blue end line and rubber snubber on 20lb balls.