the mod look good ( if the zip ties was the way as i put mine it was better because the mesh can't play when it's spin)
i can't see good but if the mesh bigger then the wheel diameter it's also will not spin. (for me it's llok good but i am not sure).
how old is this impeller maybe the magnet is lose power to and it's hard to spin when the magnet not strong and lose power.
if i am not wrong melves have the ASM sedra pump and when he compare it to the ER sedra pump the result was different the ASM was more weak.
there is another way to try it :
you can start the pump of the water and see if it's spin and then lower the pump slow to the sump (be careful not to make splash around and put on it the elbow).
you can also take out the shaft and the washer and again start the pump of water and then close the cover (some time need to let it spin by finger)
at this way you can see the reading.
IMO this pump need to run on 14LPM with the mesh and 3 layer and after day or two it's need to increase more 2 LPM alone .
if you click on the link you can see wayne_sreef was able to get on his SD9000 with 3 layer 16-17lpm .
http://reefcentral.com/forums/showthread.php?s=&threadid=966407&perpage=25&pagenumber=26
and here is my wheel impeller mod :
