my starter also didnt work on my ?13 model, so i larged the spring out. quite a lot i have to say, but this resolved the major problem. the starter works for 95% now, no matter if cold or hot. i never kickstarted the bike, i always fire it up with the electric one.
what i also did, filled the ignition case with about 150ml oil, i used castrol 10w50 engineoil. nothing swelling or leaking. i have this done about 250hours ago and the starter still works very well. last week i had a look inside, taked it apart, no wear to see. looks like the oil is doing a good job.