What's wrong with my TB-303?

I'm having problems programming patters. It's seems a bit broken/random when it comes to number of notes I can put in.

If I erase a pattern using the erase button I've understood it's defaulted to be 16 16th to play with unless I want to change it. But when I start putting in the note lengths and just use the normal 16th note I can only click it 11 times until I come to the end of the pattern. Then when I playback it seems to be 16 anyway.
If I use the pitch input for the specific notes I can also verify I can change all 16 notes... but with note length, only 11 clicks! (maximum)

Any ideas?