First identify the hyphenated Heathkit Part Number in your assembly manual Parts List, then check for that Heathkit Part Number in our website's inventory listing of thousands of vintage parts, available at https://shop.heathkit.com/ (left menu, "Replacement Parts"). If you don't see the left menu, try using a desktop/laptop browser, as cell phone browsers often do not display the entire website. If you do not find your part listed, email us with your specific need (tell us the Heathkit Part Number and the kit model it was used in--we need both) and we will check our boneyard. Incidentally, vintage kits never had serial numbers, so no need to spend an hour trying to find it.
Vintage manuals: If you need a replacement manual for a vintage Heathkit, we sell the best-available version we have in stock for each kit essentially at our cost of reproduction, bound in our high-quality modern binding. (If you find one for sale elsewhere "new" it mostly likely is a stolen/pirated copy of our books. Obviously we cannot guarantee any illegal pirated copy of our books contains the original content; and why would you expect a thief to care about the quality of the product they sell you. We hear from time to time of low-grade pirated copies of our books sold with missing pages or schematics.)
Please be mindful that many vintage Heathkits in use today are a half-century old, and sometimes the best available manual master in our archives for a vintage model is not perfectly pristine. Our website always tells you the condition of our best available master for your kit's manual when you are ordering. If you need a vintage manual, please see our Vintage Manuals web page (visit https://shop.heathkit.com/shop/ and choose the "Vintage Manuals" tab).
Modern manuals: All modern Heathkit manuals are customized to the individual kit owner and serial number. If you need a replacement manual for a modern Heathkit, please contact customer support, as this may entail custom printing of your replacement manual, deactivation and replacement of the old serial number, reprogramming of your custom MPU or other kit changes, and changes in your accounts at Heathkit.com.