Easy. Standard procedure for obtaining parts deep in the bush, which may vary slightly from one time to another: Phone call to my parts supplier back in Kampala (650km and a couple of worlds away), tell him exactly what is needed, arrange payment via GSM or tell him when I'll be back to give him the cash, get my driver at home to collect the parts and stick them on the night bus to the nearest town, 150km from here.
Then, a few more phone calls to arrange with someone there to collect the parts and put them on the next available transport - which can be a tipper lorry carrying various goods and people through the pass in the mountains, a local motorbike taxi courageous enough to undertake the journey, or a friend who happens to come this way. 24 to 48 hours and you've got your parcel, not sure if it's that simple in your countryside!
When I'm lucky, I can even get them by air on the bushplane that brings or picks up one of my clients at the airstrip in the National Park nearby, 35km drive between buffalos and elephants...
Oh, and by the way: Africa generally has a much better GSM coverage than the US or most of Europe. This helps!