It looks like they ran out of spare parts quickly and then lost the knowledge and tools to work on them. A drift away from sound practices?
I don't think Norway ever intended to keep using them for a long period of time, and always intended to stick with their original machine guns, chambered for the 8x63.
Being thrifty, smart, and frugal, they did know a good thing when they saw it, and seeing as they had a huge inventory of German equipment, consisting of just about everything Germany issued while they were occupied, they used them up until they were no longer serviceable or enough left to strip for parts.
I believe Norway ended up with warehouses full of weapons and ammunition for them when the Axis forces surrendered. They had been supplied for a long term occupation.
I spoke with a couple of people who had endured the Axis occupation of Norway. One was a factory worker, and the other was an enlisted soldier, who became a Partisan and was involved in all sorts of skullduggery to irritate the Germans.
He told me they quickly put their Krags into storage and went with German issue weapons, because they had run out of ammunition for their rifles, and plenty of captured arms/ammo were available in usable quantities without having to worry about where the next cartridge was coming from. He liked the German weapons better than their original issue equipment once he was used to them.
German weapons had a huge influence on how Norway re-equipped post war.
Germany had also shipped out the majority of Norwegian weapons to other areas, for rear echelon use, to free up other weapons for front line use, because of the tremendous losses of original issue equipment.