i have looked everywhere but it seems that here in europe dont support these kind of threat on screws like in america... may be wrong but didnt find it... it isflat head type, and with lenght of 2/8" maybe little longer...
Did you shoot Gretsch an email under their customer servise email address?Where in Europe are you?.It's probably a 8/32 x 1/4(there is no 2/8) cone head slotted screw.Just google American machine screw makers or distributors.Measure the diameter of the screw,and the number of threads per inch.In your case you'll have to multiply by for the get that number,and round it off to 28 or 32,which ever is closest.At a site like Boltdepot.com.They have photos and measurements of all of their screws.
Why not go the Gretsch website,and use the dealer locator to find a authorized dealer in Europe.Then either go there or give them a call.That way you'll get the fastest and most accurate service.
Steve B