I have an original O gauge Heljan Deltic which was subjected to a conserable amount of upgrade work including Pete Harvey etches, Bogie sideframes remodelled to represent the correct Class 55 profile. Fuel tanks narrowed plus numorous replacement cast items and finally a full repaint. Many of the most important spares dried up ages ago . If you lost any of the Brake hangers or chains hard lines, window wipers the same. Using the info supplied on the Spare parts drawing that was siupplied with my Deltic I contacted Heljan direct via their website . Their reply was a one liner referring me to contact Howes.
Fast forward to the announcemnt during 2019 that Heljan would be doing a rerun of the Deltic and thinking that this would mean fresh supplies of parts I again contacted Heljan via their website, in fact twice asking if fresh supplies of Deltic parts would be released.... No reply what so ever. I then contacted Howes who told me they were hoping to see fresh supplies especially those that had been out of stock for some time.
The fact that Howes have called it a day speaks volumes, draw you own conclusions