Check pipe from compressor to the front - along top of LH chassis rail
If this is the cause - its a cheap fix....
where abouts in the Kalahari where you? I used to live in Botswana, and loved the remoteness and amazing bush driving. We drove 130 defenders mostly, but dare I say it I had an old toyota hilux and an old SWB Samal that kicked ***.
Rich
Look forward to seeing some pics.
Cheers