Surface Mount Components

Further to my previous post about the AEG induction hob, I am now trying to repair one of the two power boards that drive the induction coils. A new board is about £300 so is not an option. Brian (Dented Porsche) kindly sent me some info. but it does not include a circuit diagram. Two of the IGBTs (insulated gate bipolar transistor) were short circuited and I’ve found I can get replacement devices from Farnell. There is a more tricky problem, however. I had quite a job unsoldering the IGBTs as the legs are soldered on both sides of the pcb. When one of them came out it’s leg must have been pressing on a nearby glass surface mount diode, which broke in half 😥 There are 2 such diodes very close to each IGBT. There are no numbers marked on them and I don’t know how to identify a suitable replacement. As it happens, I actually need 2 diodes as I discovered another one that is open circuit when checking the others with the meter. The good ones give a reading of about 0.73 volts. What worries me is that these diodes are labelled on the pcb as ZD1, ZD2 etc, whereas diodes elsewhere on the board are labelled D1, D2 etc. If the ones I need are zener diodes I would need to determine the zener voltage. I wondered if those amongst you who have changed surface mount components have any tips about identifying correct replacements?