Help:ss-DNA

[Anja]

Hello everybody,
I have a big problem in producing ss-DNA. I did that before with a pMEX as
plasmid and a helper phage M13K07 in E.coli CJ236. The method is from Viera
and Messing and seemed to be quick and easy. But now I get only very high
molecular bands (mostly ds-DNA) and only a tiny bit ss-DNA up to nothing. We
bought new helper phage and did grow the strain again under selective
pressure but no positive result. 

Is there anybody out there with a good idea or a save and sure protocol?

Please help

Anja