Another Marvel of Chinese manufacturing

[Fancy]

Was trying BK 12 Blocks and when tightening the nut it's either too lose and the screw has forward/backward play or it's too tight and the screw can't rotate :(

[m_c]

Dismantle the block and check everything is assembled the correct way.

There is history of these being assembled wrong, which gives the symptoms you've described.

[Fancy]

Did just that and all i see is just two bearings back to back.

[Clive S]

Did just that and all i see is just two bearings back to back.

There should be spacers tubes at each end as well.

[Fancy]

should i adjust the nut to have minimum drag ? or do i tighten all the way and it should be fine ? if i should tighten all the way then the block is faulty. please clarify this point for me as all my knowledge is theoretical from forums and such.

[Clive S]

should i adjust the nut to have minimum drag ? or do i tighten all the way and it should be fine ? if i should tighten all the way then the block is faulty. please clarify this point for me as all my knowledge is theoretical from forums and such.

You haven't answered the last statement ie. are there spacer tubes in the block. Also are the bearings AC type or standard ball bearings