MAC 1700 - tuner section

I have just had all the tubes and nuvistors replaced in my MAC 1700, the tuning gangs cleaned and aligned, and everything tightened and checked in the unit. The problem is in the difficulty the unit has receiving stations above 100 mc in FM MPX mode. Below 100, the reception is generally excellent and extremely listenable. Any ideas out there what the problem might be? It is not the antennae - I have a new one, well directed, and my other tuners receive exceedingly strong signals. Thanks
I would say that your tuner was NOT aligned properly after the parts were replaced. Was this service done by a McIntosh service center or an independent with FM signal generators, etc?
The work was done by a Certified McIntosh Technician (who returned all of the replaced tubes and nuvistors, all of which had tested weak or bad), and then reworked (as I watched) for two-hours employing an FM signal generator and oscilloscopes to compare the wave forms. The three-gang tuner was cleaned and aligned, and all of the other components inspected and the connections checked and tightened where appropriate. We are scratching our heads, but the bottom line is that over 100 MHz, the FM MPX works only marginally. He is not satisfied with the result at all. As mentioned, below 100 MHz, the sound truly is remarkable. Do you have any additional ideas as to what we might check?
Thanks for the reply.