I've had the solenoid fail recently too (inner wing mounted type for inertia starter) - new one lasted a week - tenner off ebay from a mini specialist I've ordered parts from before without issue ....stuck I nipped into Moss - £8 (and a few pennies) - Out of habit I don't tend to use them as they're v v expensive for some parts but they do do some very cost effective parts sometimes - added to which they're ½ mile from the office) Moss one comes in a Lucas "style" box and is significantly more weighty - surprisingly made in England too (sad that that should come as a surprise....) , spade connectors are decidedly more "solid" and it's worked happily for the last month or two....
By no means suggesting that it won't die on me - just seems far superior in quality and construction (120g heavier) - costs peanuts - so I've acquired another as a spare sat lurking in the rear bin (that normally guarantees something else will go wrong!)
IMHO I'd far rather pack a new good quality item than a used one......