I have some experience but not enough to claim any expert status.
Also pictures would help.
But in general (with the assumption that the leather is not disintegrating and the surface is not flaking off), a good starting treatment would be a soft damp cloth and some gentle cleaning with a good quality saddle soap.
This could be followed by light and periodically repeated applications of mink oil, neetsfoot oil, or a good quality leather cream. There isn't a
right choice of product here according to knowledgeable people I have talked to, but there is much acrimony in online discussions about what is
right. A general thread that runs through conflicting advice is to avoid things with waxes and synthetics.
If there is a leather work supply shop near you, you could pack the machine in and show it to the staff and ask for recommendations.
There are also shops that specialize in leather repair/restoration. They may or may not offer advice; my experience is that they are closed-lips protective of their skills that put food on their tables, but who knows? The services of a skilled leather conservator will probably not come cheap.
There is also the BBC series,
The Repair Shop, some of which is available on Youtube and various streaming channels. Look for episodes featuring the delightful Susie Fletcher, the leather work specialist.
https://www.youtube.com/c/TheRepairShop/videos
Skim discussion of my limited experience here:
viewtopic.php?t=57057