Deluxe Memory Man LFO thumping

[lwatford]

Need some thoughts on a repair.

I bought a '81 Deluxe Memory Man that wasn't working.
I've got it working and it sounds great, aside from what I think is LFO bleed. There's a thumping that changes speed with the Chorus/Vibrato switch, and it's always there, no matter any other settings with the blend up.

I'm just not sure where to start looking on this. I replaced the electrolytic and tantalum caps as well as one opamp in the process of getting it working.
I can add pictures, and whatever else you guys might think would be helpful.
Thanks for any ideas!

[Scruffie]

"Thump" or "Tick"? Does it change at all with the Modulation Depth pot?

It could be a simple case of the Chorus/Vibrato switch wires running too close to the audio so it's worth poking them about with a pen/chopstick, it could be inherent to the layout in that particular model in which case an additional power filtering cap across the LFO Op Amps power supply might help or even more 'drastically' changing it to a lower current Op Amp more suited to an LFO like a 1458 or TL062 but it could also be further up the chain.

Have you tested to make sure you have a good and steady supply voltage coming from the regulator?

[lwatford]

Thanks for the ideas. I got my audio probe back out, and the ticking/thumping (I'll make a recording later) is pretty much everywhere after the input IC. Also checked voltages, everything seems to be right (using the voltages in the Total Recall build doc for reference).

There's no change with the modulation depth, and I can hear it with everything except blend turned all the way down. I haven't noticed any change with the wire routing, I may end up changing them out, as they're the brittle old stuff that EHX used to use.

For filtering across the LFO opamp, would it just be across pins 4 & 8? What sort of value would you start with?