[Premium-Rx] Any expert on RFT EKD-500 out there?

[Werner]

Hi,
I have a RFT EKD-515 for a while. It is a kind of new old stock. Was produced 
in late 1990 and stored for almost 16 years. I had to fix some relais in the 
preselector board. It works great so far.
One strange behavior developed some weeks ago. Not a big problem but annoying: 
When tuning the VCO (or entering the keyboard or controlling the rx from a 
PC) and a "full" 100kHz mark is passed, the PLL needs some time to adjust. A 
"noise" resulting from fluctuating frequency is heard. After that everything 
is stable. I doesn't matter whether the tuning increment is 10 Hz (smallest 
step) or 100 Hz, 1kHz, 10 khz or anything in between. It is only important 
that a 100 khz value is a result by a tuning increment smaller than 100 kHz. 
Full 100 kHz tuning steps do not show this behavior. Examples:   5999.99 to 
6000.00 (10 Hz increment) -> noise. 5900.00 to 6000.00 (100 Khz increment) -> 
no noise.
Again, this only happens when going over the 100 kHz mark. All other frequency 
are "normal".
Any EKD experts out there with suggestions?
B.T.W: I have all the schematics an  the repair manual.

Regards, Werner