Had some luck with this one from the first test;
each dozen consists of three horizontal column streets. (4 numbers)
for an example 3,6,9,12 is a column street.
Trigger: first spin, bet the two unhit column streets in that particular dozen hit. as a second dozen hit, bet the 2 unhit column street in that second dozen also. do one spin, if no hit start progression 2,3,4,5,6 ...and so on (+1u bet for each loss). if the third dozen hit, bets are changed into the two last dozens hit...two last doz' unhit column streets hit are always bet.