Global Scale Modeller

you use cutters right?

how old is the model?

You could try heating a scalpel blade or hobby knife blade (would work best with a scalpel though) a little, this will give the blade a little more 'slide' as it cuts through. Be sure to cut well away from the part thought as there will be a very slight melting action going on...

Worth a try

Hendrik... myself I would have stopped after I broke three or four and started looking for a cheap aftermarket set.
I have very little patience for that sort of thing. Fun stealers are not allowed in my man cave.
Those tracks sound like they qualify my friend.
Kick them to the curb and try something else would be my advise.