The main problem with the Hallmark diesels are the gears,which crack and split,especially on early models. They are white plastic. I believe some later locomotives used brass gears. Hallmark was good about sending replacement gears. I still operate my Northern Pacific passenger scheme F-7 A-B locos and have not had any gear problems. My other locomotives F-7's and F3's in UP,GN,and WP are stored away as are my Hallmark FT's in A.T.S.F. & Rio Grande. I'am sure they are worth some money to collectors. Newer locomotives in Plastic from Intermountain, Micro Trains, Kato have as good or better detail and a lower operating speed and have replaced brass in my diesel fleet. Ntae Goodman (Nato). Salt Lake,Utah.