Spectrum Analyzer (AT6011)

We have two of them ATTEN type AT5011A Spectrum Analyzers w/ tracking generators, from China bought about 18 months ago from two separate suppliers in China.They both worked ok for basic production work for about a year and then we noticed the generators falling off in output on the high end and gradually getting worse. Both suppliers don't seem to understand or co-operate. We would like to send both back for repair. We are manufacturers and if anyone has a problem with our product we are most interested to see the unit and repair for free and then we have a staff QC meeting to see what to do about the situation or who made a mistake etc. Its a very valuable learning experience for us. So our trust is still in HP~! Our 141 has been doing a good job for 20+ years and the HP Network Analyzer is the choice of all our techs. The ATTEN would be ok for some work if we had tech support or could trust it.