Hi Paul, There's no denying the Bachmann class 108 is a lovely model, and I'm sure you can't wait to get the wheels spread to something more realistic!
The biggest bugbear of mine is the orangey colour of the yellow front ends, and it's more noticeable when placed next to other locos / units, even though there were many shades of yellow to be seen on the real railways. Weathering and exposure to sunlight also makes a difference....... so ........
In an attempt to get rid of the horrible vertical moulding lines on the front end (by easily scraping with a knife blade), it will improve the looks of the unit(s) and a quick wash of proper yellow, to match the already excellent work you've put into this project so far.