Re: Why is voiding of warranty a problem?
There's another issue - where the warranty might only cover certain parts (or there might be different warranty lengths for different parts) which is common in things like printers with lots of moving parts. As an example, some years ago we had a few "not very cheap" label printers for producing the product labels to go on the stuff we made. The barcode requirements are quite strict - and if substandard, some large retailers will simply return all the stock to you. We even had to have different printers for different barcode sizes - it's to do with the elements*/mm in the print head.
If you've ever looked at a barcode label and seen white lines across it (normally in the same direction as the lines in the barcode run) then this is normally a sign that there's a broken element* in the printhead that made it. When you've a printhead something like 100mm wide, with 300 elements*/mm, then it only takes a tiny bit of grit to cut into one or more elements* and you need to replace the printhead. Even if you keep the place very clean (and this is in a factory), just the wear of the ribbon passing over the printhead will eventually start taking out elements.
We went through a bit of "discussion" with the printer supplier until they pointed out something they'd never mentioned when we were buying the printers - the printhead was explicitly excluded from the warranty (and no I don't recall whether anyone read the very small print). To avoid the man hours costs, we got one of our own people trained in how to replace and align the printheads - something that happened every 2 or 3 months IIRC.
So in this case, you've got a situation where there's a non-warranty part replacement required - and you'd not want the manufacturer disclaiming the warranty on the rest of the machine because you replaced the consumable part yourself. Note that the consumable part wasn't a "click out and click in" replacement - it needed partial dismantling of the machine and then careful alignment afterwards.
* For those that don't know how such things work ... These were thermal transfer printers, where a sandwich of backing carrier (waxed paper), label, and wax coated plastic ribbon passes under a printhead and driven by a rubber roller that both drives the labels along and applies pressure to keep the labels, ribbon, and printhead in contact with each other. The printhead contains lots of small resistors, which when powered will heat up enough to melt the wax so it transfers from the plastic ribbon to the surface of the label.
For barcode applications, dimensional tolerances are quite tight - so you always try and print the lines of the barcode along the direction of travel of the labels. That way, the lines (especially the "cleanness" of the edges) is defined by the geometry of the elements and not by how fast or slow they turn on and off. If you print them the other way, the lines are not as crisp as the elements take time to heat up and cool off - and this can vary between elements as well which makes the lines slightly jaggy as well as fuzzy.
It may not be immediately obvious to those accustomed to (eg) modern laser printers which will scale a font to any size and print nice smooth text, but you can't do that with barcodes. Each element in the printhead must be either 100% inside or 100% outside of the line you want to print - if it falls partway then you end up with a line that is either too wide (element turned on) or too narrow (element turned off). This means that for each size of barcode, you must have a printer with one of a set number of elements/mm in it's printhead. IIRC we had a 208element/mm head machine for printing "80%" barcodes (that's 80% of the nominal size laid out in the specs) - with a 300element/mm you could only do a 75% barcode, and some retailers refused to accept that size even though their tills would happily scan them. "The spec says 80% minimum, so we're applying it because we can" mentality from certain buyers - we even had a case where a retailer had accepted 75% barcodes for years, then the buyer changed and refused to accept anything smaller than 80%.
Yes, being able to talk about EAN symbologies is a quick way to get labelled a geek at social gatherings !