Well, pin 14 on the TDA 1047 is sitting low and that's directly related to the signal strength meter drive circuit. I'd be suspicious about C209, 22uF electrolytic. If it's shorting that would pull this pin low.
What voltages do you read on either side of the center tuning meter? Does that meter move if you adjust R236, the variable pot for setting center point?
Also pin 15 is sitting high, and I don't see a likely cause for that. Could be the IC isn't healthy. Remember this is also the IF amplifier, so if it's out you aren't getting sufficient signal into the stereo decoder.
I think pin 1 voltage label for the MC1310P is wrong in the schematic, probably. If you trace the line from that pin, it passes the filter cap C801, then series resistor R808 47 ohm and then ties directly to the 14V +/- 2V output from Q202 that supplies B+ to this part of the tuning circuitry. That ties to the datasheet layout. BTW you can look at a circuit description for the MC1310P here:
http://www.circuitstoday.com/stereo-decoder-circuit
The high reading at pin 6 is consistent with no stereo, that pin goes low when stereo is detected. BTW, keep in mind that these use an LED for a stereo indicator and it's ridiculously easy to plug the LED into the 2-pin harness backwards; doesn't break anything usually but worth unplugging the connector from the LED briefly to see if it is connected with the correct polarity.
I'd check C209, probably could just remove it temporarily and see if that brings the signal up and causes any meter activity. After that I'd probably try replacing the TDA 1047.
Mr. Nick, here's where we don't see quite eye-to-eye: it's bad practice to start replacing components in a device with no probable cause other than they are old, particularly in a non-functional part of a device. You simply introduce more variables to the process of tracking down the root cause (even if it's done correctly), and almost certainly introduce new issues if it's not done correctly. The exception to that in my mind is when the technician is very familiar with the specific device being serviced and has repeatedly found that failures are caused by mass component aging, then a blanket part update may be justifiable. I don't know whether you're at that point with this model (or series of models, the FM tuners are almost identical across the range) but I've never had to replace ALL of the caps to make one work, in fact I can't remember the last time I found a single cap failing in the tuner such that the tuner was non-functional to the extent this one is. Other areas like the power amp, preamp, regulator circuit, yes - but not the FM tuner. Same for the ceramic filters, by the way, I have never had to replace one over the past ~15 years of working on these as a specialty.
It may well turn out that a bad cap is responsible here, but since Peter has shown good ability to take direction and look for issues at the component level, and overall is making decent progress towards tracking down the specific issue, I'm of the opinion he should pursue that to a logical end and not just start throwing parts at it simply because the originals are now getting on in age. If he first gets the tuner working well and then wants to recap to help add some preventive measure towards the future reliability, that's a different discussion.
John
I did some measuring this morning on both the IC's. I double checked the measured voltages and I think there is something seriously wrong with the voltage on pin 1 of the 1310 IC. It reads 12,58V where as the manual read 1,5V! The other values on the 1310 ICseem to be reasonable?? The values on the TDA 1047 seem on some pins a bit out, but I don't have the knowledge to judge this. Hope these figures will help solving the problem. I am very curious what you think of it.
I could use some result because it take a lot of stamina to get this machine running properly again 
