Ernest Doe & Sons in Essex can do one & post it to you, they can do any currently available parts for the 350.
www.hancox.co.uk are Kohler engine specialists.
Try Hancocks in Birmingham They are agents for Kohler and can supply most things Good luck gettting the fly wheel off, you may need some help My 350 wouldn't spark when I had it, so i decided it was the coil, it wasn't, it was the points, just a thought Coil is available as a coil, or coil and back plate. If ou can get the coil and back plate, as it reduces the dismantling you have to do, and the soldering. Be warned, they are not cheap
Luckily I have a rather strong and helpful neighbour who removed the fly wheel for me (being just a weak and feeble woman ) . I've already replaced the points so I know it's not that. The only other thing it can be is the coil as it does look at bit 'ropey' and worse for wear.
Hello Coils always look ropey If you can get it off, take it to your local garden machinery place and get them to test it before you condem it . If it helps my Kohler was fitted with new points when it wouldn't start, they had not been set correctly, this may be worth a check, as would be the Kill switch and wiring The kill switch can rust and caiuse a short to earth, just like turning the engine off, so a check here may be helpful too. Good luck
Just thought I'd let you know, thanks for the contact info. I spoke to a really helpful guy called Steve in the sales dept of Hancox who sent me the exact part I needed. I gave him my award for Customer Service experience of the year as he was brilliant!
Rotovator is now working and I have a fully rotovated plot!