Further to your questions: The tape heads in the later Fridas are built by Advanced Magnetics in Belgium. The transport is fairly direct and handles tape quite well. It will rewind and fast forward at an extremely high speed...scary in fact, rewinding a full 2500 feet in less than a minute. There is a goto button that will take you back to the last stop point or if pressed twice back to zero. The transport appears to be based on a constant feedback monitored series of optical sensors. The feed and take up motors are regulated to approximate the speed you have selected, and then the capstan motor is designed to lockin at either 3.75, 7.5 or 15 ips. This too is feedback monitored and yields a very low wow and flutter when locked. The Frida does not like cold I have learned and will not lock at 15 ips if its below about 50 F. This can be a problem on startup after sitting all night; you need to provide sufficient warmup time. There is a varispeed as well which is very nice when editing and can even close in on a fair approximation of 30ips, but certainly not without some wow. Level, EQ and bias trimmers for each speed are readily available under a flip up cover between the key board and the heads. There are also switches for NAB/CCIR, Calibrated and variable record and plaback, tape speed or timer select and some self test contacts in the Frida I that allow the internal computer to check all electronic functions.
As Rich Brown previously mentioned the Frida II has a scrape flutter roller and if this part can be located it could clearly be retrofitted to Frida Is.
The PPM meter on the Frida II I suspect has an adjustable response rate. I am hoping to confirm this when I get the newer manual. What I noticed was that on mine it seems to read like a ballistic VU meter. I think this is probably adjustable since the earlier Fridas all work on instantaneous response.
When in the horizontal position (which is my preferred way of using the machine as opposed to vertical rack style positioning) the front panel under the keyboard is easily removable and allows access to all the trimmers. Lifter and pinch roller position and tension, feed and take up tension at speed and rewind/ff, Odb Level, erase bias level, speed lock and stability trimmers are all front accessible. I usually leave these panels off all the time except when transporting the machines. Each time I do a dubbing session I do a full run through of these settings per the operation manual.
The lines in and out on the rear are balanced XLRs, and the operating voltage level and fusing is readily accessible. One drawback is that the Fridas are a bit noisy in operation. I think this is because they are so small and do not include any sound insulation. And certainly the way I use them with the front panel off this is aggravated. On mine I have disconnected the cooling fans which are only needed if the ambient room temperature is around 100F. I have also disconnected the tiny playback monitor speaker since it is automatically on when you go into adjustable playback level which may be needed during dubbing. It would be very easy to retro fit switches for both of these functions.
Rich Brown mentions that the headphone playback is "crappy," but I certainly haven't found that to be true using my Sennheiser HD590s. According to the manual it is also an aux unbalanced line out and has its level controlled by the variable playback pot. I never use it, so my opinion here might not be particularly reliable.
On the back of the main audio board are a series of jumpers to adjust the input/output/record/pb level ranges of the machine, but for the life of me I still haven't figured them out. On all my machines they have come set in one position, so I just leave them there. From talking to the Lyrec staff before they went out of business these can be used to accommodate different studio line level standards against different flux recording standards. Supposedly it covers .775/1.23/1.55v SLL and 250/320/510. I operate my units to a studio line level of 1.23 volts and at 250nW/m. Occasionally I will reset a machine to 320NW/m but I find using Agfa PEM 468 the 250 level gives a very nice recording.
I doubt these Fridas are for everyone. I got into them because I travel a lot with my recorders and with a bad back a professional machine at 25 pounds is a lovely find. If you have a permanent setup I imagine the heavier machines are just fine. I used Techincs 1500s in ATA travel cases previously and still have them. They are certainly very dependable, gentle on tape and sweet sounding. But the weight of them has led me to retire them and I imagine now that I am settled on the Lyrecs the 1500s will be available to a new home soon.