You will need to spend a lot of time grinding the glass down, wear a face mask. Really deep scratches, this is not going to work.
I suggest to clean the tank once it's broken down: clean razor blades, change them out frequently.
Clean top to the bottom, then pull the plastic scaper away from the glass, wipe and then go top to bottom again.
Never side to side. Wipe any snails off the glass first.
Careful not to get any sand between the scraper and the glass as you near the bottom, if you do the top to bottom method, this will not happen.
Pads get snail shells, and bits of gravel caught in them.
This will scratch the glass later, so change those out often or do not use them except in the upper parts away from the gravel line.
Silicone corner,s bleach for the broke down tank, Excel/H2O2 for the tank when fish are in it while doing a larger water change, take a toothbrush to it, preferably your wife's.