Thanks.Checked through instructions csrefully, which seem a bit 'generic' They are open circles rather than discs, black in colour. But judging by the size and slightly soft material I think you are right. Thanks very much most grateful.
I hope this isn't a silly question. In the GWR HST set in a small neat plastic bag, located the section with the buffer stops, are two small plastic circles. What are they for, please? Thanks. Howard