clustering

It was obviously the return spring failing in some way which was preventing me from shifting chainring but was't obvious until the mechanism was removed whence the little bit of metal I found on the floor after cleaning the offending area had snapped off. To slightly compound the annoyance caused by having to replace a mechanism which is merely six years old, whilst I was in that general area I installed the replacement chainring I bought three months ago to replace the severely-worn one I had temporarily replaced with the middle ring from the old one I'd uninstalled eight months ago only to find (as it hadn't been an exact match seeing as an exact match was unavailable) that it causes the chain to scrape the large chainring slightly when on the middle chainring and smallest sprockets, leaving me with only six or seven gears (probably all I use in a normal day but all slightly lower-ratio than I'm used to them being) until I can replace either the chainring (but only with the exact type) or front derailleur. One of the latter has been found locally and might be able to be installed tomorrow, though will probably be merely bought until next weekend.