Where do Tweets go to die?

This has happened to me. Sometimes I can only get to page 2. Sometimes, it is page 6. Sometimes I can't get past page 1 at all. But it's a feature that changes. At most, I can get to page 10 and I just wondered if older messages are deleted or archived somewhere.

No answer from Twitter. Do they even monitor their customer question pages?

This is Twitter's pagination problem. Have a look at other topics which are tagged pagination, too. At least one is being followed by a Twitter employee, so you may get more attention there. The related topic Why Older button is not working? which includes an answer by crystal from Twitter, may also be of interest.

When I first started using Twitter (in late April) I could follow my timeline back 20 pages. Since then, as usage and the number of users increased, Twitter became ever more unreliable, and its creators have been limiting or turning off parts of the service which represent a particularly heavy load on their system. This includes pagination - the number of pages it's possible to go back in time. Various components of Twitter are also being reprogrammed to make them more efficient, so pagination is likely to improve some time in the future.

The Twitter Status page displays current information about individual Twitter components in its sidebar under the heading

Status per Feature

The colours indicate

Green = All systems OK
Orange = Not in full working order
Red = Offline

If the mouse is moved over the coloured bar, somewhat more detailed information shows up,

e.g. pagination: Some users will miss OLDER link.

I don't know for how long Twitter keep older tweets, but sites such as quotably.com appear to archive even tweets which have been deleted - embarrassingly including some of my own tweets in two or three preliminary versions which I'd deleted after re-tweeting them with corrected spelling etc...