Cartridge problem, phono warm up? Other problem?

Scenario:

Grado Gold cartridge, SME tone arm on Thorens TD 125 MK II
Grado PH 1 phono stage
USBPre A/D converter
Recording on OS X with Bias Peak.

My main problem is a noticeable loss of deep bass resonance in digital recordings of my records.

Symptoms based on testing:

Comparison 1:

A. Kraftwerk Autobahn recorded two weeks ago when PH 1 had been running 24/7 for weeks. Not sure about tone arm balance at this point. Stylus had been exposed to some scratchy, dirty records. Not much liquid cleaning of stylus.

B. After phono stage had been turned off for a few days, warmed up for 48+ hours, tested Autobahn again, before and after two attempts to recalibrate SME tone arm. Prior to this test and power-off of phono stage (2.5 days), but after earlier recording, I had recorded several scratchy and dirty (soapy residue?)records. I have noticed a reduction in bass in recordings made before the power-off, so that may not matter. As for the records, I cleaned them as well as I could before recording. The residue was due to earlier problems caused by previous owner.

Result of comparison: Original recording has very deep, resonant bass, highs are there. Tests since then, after tone arm calibrations, show decent bass, but lack the very deep bass of the earlier recording.

I'm not sure what the state of the calibration was when I made the first recording, but when I checked it after the power-off, the stylus had gotten "lighter" rising above the record. I wonder if the "bass" may have been due to the stylus riding higher in the groove somehow.

Comparision 2, between recording and lossless digital version of the same musical track (possibly from CD).

The digital shows deep bass, just as the first Autobahn recording showed.

The record recording bass sounds okay, but noticeably lacks the deep base in comparison with the digital one.

This could be due to an old vinyl vs better source, I don't know.

Another strange thing today is that twice now, while recording, the system has suddenly generated 100% white noise. I have no idea why.

I asked Grado about the bass issue, and a knowledgeable source there warned me about using liquid on the stylus (no feedback about phono stage warm up yet). At first he said just be careful. I was, but later he explained that if liquid should move up the stylus shank into the generating system gradual degradation can occur.

Because of the dirty records, I was concerned that the stylus could have picked up junk that would not come off with just a brush. So I applied distilled water to the brush.

Now I'm concerned that liquid might have made it up to the "generating system" and could be responsible for the lack of bass. I am also worried that the two instances of 100% noise might be a sign of the cartridge failing.

I realize this is a complicated problem/question, so please bear with me. I hope someone can explain this.

I'm doubtful at this point that the phono stage has anything to with it. The SME arm may need some lubrication at this point to be sure it is balancing correctly. I don't know how it got out of wack from the earlier calibration some weeks ago. It bugs me that the arm can be that sensitive. But it is problematic that I can't reproduce the earlier good bass from my first Autobahn recording.

I'm in the process or digitizing a huge collection of records to digital, so I need to get a handle on this! ;-)