Vintage Microsynth sweep debug with revised schematics

[Ngr]

Hello everybody,
Please take a moment to read and possibly help me.
I have on the bench an old Micro Synthesizer that behaves quite strangely:
when powerd on it takes 30 seconds or so for the effect to come alive and, if a guitar is played, it comes on with a huge sweep. Maybe related to that is the fact that the sweep does not work properly: or better it's not working at all. Start and stop frequencies appear to work but I can hear a sweep only when I'm moving the start and stop sliders. The rate slider changes the character of the sound but no sweep comes on. I managed to troubleshoot all of the other features (it was completely in pieces, not a wire was soldered to both boards) but not this one.
Where should I look at?
I replaced U9 and A13, as well as Q3 and C28. D16, D17 and D18 appear to be ok.
I forgot to mention that I must set the trigger slider at its minimum since pushing up the slider makes the pedal silent. Maybe this has to do with my problem.

Is there any critical part to look at?
Thanks in advance for your attention.

Below is a new version of the schematics without the mistakes and omissions.

https://www.docdroid.net/u3cx2Xj/electro-harmonix-micro-synthesizer-revised-2017.pdf.html

[R.G.]

As a general rule, any time you're given an old [whatever] to work on that's more than 10-20 years old, your first move should be to make a list of 100% of the electrolytic caps inside it, order them, and carefully replace them all.

Electro caps rot in place over a decade or more. Many, many times, replacing all the electro caps is all that some vintage effect has needed to run like new.

It is NOT a waste of money to replace them all even if only one is currently bad. If you had some way to know the one bad one, another would go bad soon. Even if all of them are just barely good, one will go bad soon.

Worse, if they're all just barely OK, they can be leaky enough to mess up your finding the other bad part(s).

This is one of my two departures from measuring and knowing the circuit operation before swapping parts. I think it's justified because it adds decades of trouble free operation into the "victim", and it's nearly always cheap in both dollars and time.

[Ngr]

Thanks for your reply,
indeed I already changed all of the electrolytics. This I always do when restoring an old effect or amp.
I managed to make the trigger work again by substituting a 4558 and now the effect is correctly sweeping. But now the attack delay works only when trigger is set very high. No matter what setting the gain trimpot is set at!
This is giving me headache.