Not sure if this is a new idea but I'm going to fashion a kickstart return rubber from the heel of an old worn out pair of army boots.
Its supposed to be oil resistant rubber & I'm going to see how resistant it is, coincidentally they are worn out partly from kickstarting motorcycles so the whole thing seems to flow .. : )

Fred,
Have a look at your boots and try to determine what the heel material is.
These days it is likely the sole and heel are moulded from polyurethane.
If so, it is my experience that when constantly subjected to oil, polyurethane breaks down into crumbs.
I concede there may be a suitable grade of polyurethane, but I have yet to experience it.
Some years ago when I had a lot to do with Hydraulic machinery, some bright accountant decreed that many seals would be made from polyurethane. Most of them made it out of warranty before they all failed. Try to imagine a complex machine with dozens, or even hundreds of valves and other precision components all jammed up with crumbs of polyurethane. Understandably, some owners were very unhappy chappies.
Which is why I use Nitrile rubber, or Polypropelene, as per my gearbox post in Technical section.
Neale

email (option): n.gentner@bigpond.com

Neale, thanks for that, I cut 3 into shape & will immerse one in the same oil in a jar & check its progress.
If it fails i will replace with Nitrile or..
The other thing I had in mind to try was those synthetic wine corks .. I have several different types which all seem to have good damping/shock absorption, think they might be polypropylene, I will make on oil test on some of those after cutting to shape.

I believe you can still get NOS from Russell Motors....Ian

email (option): ian@wright52.plus.com

There's a few options if I was to simply buy one but I'm looking for a source of material from something I throw out, I've always been dismayed to see the state of the standard ones on opening up a g.box.

Ian,.. you haven't by any chance got a gearbox clutch control lever of the shaped type available ? its dimensionally as WM20 but the shaft is waisted & tapers toward the top.

There is something unstable about the soles of modern industrial footwear, even the types labelled as oil resistant. It has only a limited shelf life. We regularly throw unworn boots in the odd sizes away at work as the soles fall apart in the boxes.

However, if you're talking about the soles of Boots, Ankle, D.M.S. then they're indestructible. Probably designed to withstand nuclear attack.

email (option): 79x100@gmail.com

Yes, there's some rubbish footware about, I said "Army" boots but maybe i should be more specific, I'm referring to MOD issue Assault boots (DMS sole). that's what I've been wearing for years, they are a superb product.
Anyway the test is underway & I have 3 rubbers shaped on my bench grinder now in a jar of oil. 1 from boot heels & 2 from synthetic wine corks ... I will check every week what happens.
they are half submerged.
The wine corks look very promising : D

'I need a new gearbox rubber...I'd better drink another bottle of wine'.. ...Ian

email (option): ian@wright52.plus.com

Surprising how often they need changing the Bordeaux corks only last a week at best ; )

I've tasted some of that cheap French wine... the plastic corks need to be acid proof

email (option): horror@blueyonder.co.uk

Hi Horror...Put some Creme de Cassis in it..or one of the other varieties of that drink made with different fruit (Creme de Mure..my favourite..or Creme de Fraise)...It makes cheap French white wine very palatable...Ian

email (option): ian@wright52.plus.com