18w Liverpool transplant-seeking constructive criticism

[tomrasdf]

Well, here's my second build. The original circuit in this amp was a bit of a disaster (see "before" pic), but I just couldn't let so cool a cabinet go to waste. It's not as pretty as most of the builds I see posted here and definitely not as well thought out. I tend to be impatient (something I'm going to have to get over it I intend to do more of this.) But with the exception of some limited issues, I'm very happy with the results.

For a schematic, I used the newest Liverpool schematic with a 1.7k (rather than 1K) dropping resistor before the screens and cathode resister value from a Marshall 18 watt. Bright switch is still in the works.

Because of the tight space, I had to get creative with the power supply. The options I considered were mounting them fender style underneath the chassis, or the one I went with. As I'm at school and don't have access to a decent drill for mounting holes, I went with the easy way. I haven't discerned any negative consequences from my decision yet.

I have a trim pot for the grid load resistor before the clipping stage. I'll probably replace this with a fixed value when I find a sweet spot. I also have a balance pot on the PI plates because I was curious to see what difference it made. I'll probably swap that out when my curiosity is satisfied.

The lead dress is a bit long for my liking. When I get some free time, I might experiment with mounting the tone caps right on the pots to reduce grid wire lengths.

ISSUES: When I turn the treble and presence all the way up, there is a fast, percussive sounding oscillation, as well as some hiss. It's not noticeable with the presence below about 7. The hiss is dramatically reduced when I move away from the amp. Is this a normal thing? Grounding? Bad heater supply layout?
I've also noticed a slight parasitic oscillation riding the high notes. It's really only noticeable when using the neck pickup (humbuckers). Not to bad, just makes it gives it a slight unmusical edge. Also, though I think it sounds pretty good, it doesn't seem to have that magic sparkle. The harmonics are there, but they're not tangible.

Any constructive criticism is welcome. My goal in posting this it to be better prepared for the next build, when it comes. I'm most curious about any problems that may result from the close proximity of the PT and OT and everything else I have crammed into that half of the chassis. Would that negatively affect the amp?
Thanks all for comments and for contributing to this forum. It's been invaluable.

[tomrasdf]

More pics

[tomrasdf]

I apologize for the akwardly massive size of these pics. I'm new at this whole electronic media thing.