I had 2 rear mushrooms 2 years ago, I had to have a word with my neighbour the old school wayChased the garage up about my tyre, they hadn't located the leak either - so were reluctant to take the tyre off; but it is leaking, so I asked them to go ahead. With any luck it'll be something they can put a mushroom plug in.
Fitted the 15 tooth front sprocket, so looking forward to getting it all back together - if the weather is good on Sunday, then I'm.off out to rip up some.backroads