I was doing PCR for a month day everything was going ok suddenly I saw smearing in the second time I was doing PCR using my primary PCR product. I started series of troubleshooting later even my primary PCR is showing smearing. The smear appears right from the wells. So far I have changed the PCR mastermix, new primers were diluted and used, new water, the only thing I didn't try is to use new running buffer. Now using positive control during troubleshooting I am seeing smearing around the right band size tough I don't see the band clearly.
What do you suggest? Please need help urgentlyyyy. Thank UUUUU