A couple of questions.
What voltage are you running the flex mods at?
Are you sure they are 1 ohm? might want to bump it up a little 1.5 ohm maybe?
How good is the PBS? Is it ar coated?
And double check the polarization. It will be arc seconds rotation to get it dead nuts. Do you have a power meter? Or can you rig a Si photodiode with a ND filter to get a relitive reading? you should optimize each diode rotation with a meter if possible.
Do you have lasorbs? If not you should have them just for peace of mind, and they work.
chad
When the going gets weird, the weird turn pro.