I think we ought to point out that BlackC55 is one of our more knowlegable and very informative members. His list is extremely comprehensive and gives you an excellent check-off list but I doubt you will find many, or any of these faults on a well presented, well looked after model? Don't be put off by that excellent post, I would suggest 'Fore warned, is fore armed'.
Are these engine quite noisey, or have they now improved?
Good luck in your quest and welcome to a great forum.
Regards
John