I've been having a little difficulty with 293 cells. They are not very adherent in the best of days (don't even require trypsin to dislodge them from the culture flasks), but it's been proving a disaster when I try to culture them in 96 well plates. We need them for RNAi experiments, so I really have to have equal amounts of cells in the wells. The problem is that at the washing steps, the ice-cold PBS simply washes patches off, no matter how careful I am. And I've been careful: adding the PBS dropwise onto the walls of the cells... it's taking a lot of time to do 20-30 samples, let me tell you

(Strangely there's no such problem when I tried it on bigger plates; the only problem is, of course, that the reagents are a tad expensive to conduct the experiments in 6 well format.)
I thought about using EtOH or something similar to fix the cells onto the plastic, but I'm not really sure if it would work, and if it would interefere with the lysis, RNA isolation and qPCR. (I'm very new to cell cultures.)
I'm sure people use these cells in similar settings - please give me a few pointers what I could or should try.
Any help is much appreciated.