I think 6. The ABCD terms in what follows may be constant between moves but don't have to be - it's unimportant;
o is open, s is shut, x is unknown
1 Pick two adjacent lids - open both AoBoCxDx
2 Pick two opposite lids - if one is shut open it
assuming no bell position has to be AoBoCoDs
3 pick two adjacent lids - if one shut open it - success - however if both open shut one (doesn't matter which)position now either 1) AoBoCsDs or 2) AoBsCoDs
4 Pick two opposite lids - if both open, shut, if both shut, open, success, position was 2)
- if different leave alone, posistion 1)
5 Pick two adjacent lids - if both open, shut, if both shut, open, success
- if different swap, i.e. shut the open one and open the shut one position now AoBsCoDs as in 2) above
6 Pick two opposite lids - if both open, shut, if both shut, open, success