Re: breech; I try and always leave mine open ('cept when taking a shot!). No load on any of the parts that way. Only keep it closed between lanes if it's peeing down or it's really dusty. How does the breech seal o-ring look? was this replaced recently? Does the breech close really lightly (possibly too lightly)?
Re: barrel cleaning; I've had my shutz for about 5 years now and i still haven't figured out the best cleaning regime, it doesn't spit them out all over the shop like yours though
2002's are aparently quite easy to take apart. I've accessed the valve on mine before so could show you how to do that. Never looked at the hammer but it can't be too hard. I would think a fault in this area would result in lower velocity, which way do you fliers fly??
How does she group with the Welham air-stripper thingamy removed??