Such gremlins aren't acceptable on a £100 loco never mind a £160 one. I'm glad you found a way to remove the chewed screws. It typically is possible, but the methods can vary from elegant to downright ugly.
What people need to remember is that no matter what you buy, be it a loco, vacuum cleaner, fridge, or whatever, the cost of poor QC in terms of warranty returns/repairs *always* gets passed onto the poor customer in the form of higher prices. And it can be avoided.
RWJ