Chris's camera pages
Finding the camera parts you need for your D.I.Y repairs
Whenever you start looking for replacement parts for old cameras you will likely find that the original manufacturer has long since given up stocking spares.
This still leaves a few options. If the camera is popular enough, and the part you need is frequently required, then you may be able to buy replacement parts made by a third-party.
The second option is to buy the same, or a very closely related, model of camera to act as an "organ donor". Dead cameras can often be bought on Ebay for around 25% of the price you would have to pay for supposedly good example, of course you are dependent on the seller being honest in their listing. The challenge is to find one that doesn't have exactly the same part broken that you will need for your "transplant recipient".
So, what parts fit what camera exactly? Certain parts are common to more than one of the Retina & Retinette model, which is very useful to know when hunting for a parts camera.
For example.
The shutter-cocking racks in the Retina Ib, IIc, IIIc, IB, IIC, IIIC, IIS & Automatic III are identical to each other.
The shutter-cocking racks in the Retina Ia and IIa are identical to each other, as are the frame counter springs.
The shutter-cocking racks in the Retina IIIS, original Retina Reflex and the Reflex S are identical to each other.
The shutter-cocking racks in the Retina Reflex III and the Retina Reflex IV are identical to each other.
The exposure-meter movements in the Retina IB, IIIC, IIS, IIIS, original Retina Reflex, Reflex S, & Retinette IIB are identical to each other, though the plastic housings differ, and there is a lot of fiddly work swapping them over.
Lens components in the IIIc, IIIC and original Retina Reflex are largely identical to each other. You can use the rear reflex lens component in the rangefinder bodies, but not the other way around, the rangefinder rear group does not clear the reflex mirror. No problem with the front groups. If you were planning on changing from a Schneider to Rodenstock lens set, or vice-versa, that option is full of fishhooks, I suggest you don't go there.
The third option is to ask if another repairer has the right part in their spare parts boxes that they are willing to give, sell, or trade to you for something else. Here are the links to a couple of D.I.Y camera repair sites where you may find people who may be able to help you with advice, and perhaps the part that you need.
The Classic Camera Repair Forum The original forum is long-gone, but you can view the archived postings here.
Yahoo groups Camera-Fix Group.The fourth option is to watch for auction lots of camera repair parts of the right type being sold on Ebay, or elsewhere, as a retiring camera repairman sells off his old stock. This is how I have generally bought most of the commonly used parts that I rely on for repairing cameras for myself and others. Buying parts this way will require a bigger initial outlay, as you will be buying the whole parcel of parts, not just the part you need for one particular repair job, but if you plan on repairing one particular brand of camera frequently, then the investment may make sense. Take care to be reasonably cautious, a lot of of the shiny parts are available at this late stage simply because you are unlikely to ever need them.
Beyond these options, just do an internet search yourself.