I have upgraded my Linn with what I feel are sensible upgrades eg. Cirkus bearing, Majik subchassis and Rega rb330 arm.
Each of these items work together in a mechanical manner to produce a solid basis from which the cartridge can work.
I wonder whether the linn detractors have listened to a well set up deck that is on song.
Mine has been set up by myself and when persevering to get it right it can be plainly heard when it is not quite there and when it is singing.
I don't know about putting a really good arm on it. It probably depends on the state of your particular example: Abbydog mentions play in the bearing and mine bears that out: both the 160 I had and the 147 I still own were much better. And then there's the motor: many develop a tic-tic, or have a slightly bent spindle, and decent replacements aren't cheap or easy to source. I don't think a less than ideal example is going to major on detail so fitting an arm with strengths in the areas of detail or subtlety might not yield especially impressive results. Mine didn't suit a Nima, which sounds really good on my Gyro. But with an RB300 it really punches out the music. A different mat also helped clean and speed up the sound on mine: I splurged on an Achromat but a cheap felt one was also much better than the stock Thorens. A posh Origin Live belt also made a very noticeable difference - although I wouldn't actually recommend it: too wide (I took a knife to mine).So if I stick with the 125 instead, what would be a serious arm upgrade worth checking out? I've had an SME 3009 and it didn't sound any different to the stock arm, worse in some cases.
I don't know about putting a really good arm on it. It probably depends on the state of your particular example: Abbydog mentions play in the bearing and mine bears that out: both the 160 I had and the 147 I still own were much better.
Having worked on both I can say that the mechanical build quality of the 125 is on the same level as the 124 Tony. Think of the 125 as a belt drive 124 if you see what I mean and you'll get the right idea.
I agree with Sean, the weak link is the motor from my experience. There are several different variations of the motor and pulley and I was only 100% satisfied after swapping out the motor on mine to one with a different pulley/spindle design and then fitting a fancy machined alloy aftermarket pulley.
The electronics also need to be in good order and set up properly.
The whole bearing housing can be replaced on the Mk1, AIUI, but not the Mk2. With mine (Mk2) it's just a case of it not being a very tight fit. The 147 is much better in this respect - but like the 150, the sub-chassis is pretty light weight. The 125's is really very substantial. Some day I'll put the Rega arm on the 147 to see what makes the most difference.What is the cause of the bearing play? Chances are it can be fairly easily fixed by replacing the bushings, that is certainly the case with the TD-124 anyway.
The whole bearing housing can be replaced on the Mk1, AIUI, but not the Mk2. With mine (Mk2) it's just a case of it not being a very tight fit. The 147 is much better in this respect - but like the 150, the sub-chassis is pretty light weight. The 125's is really very substantial. Some day I'll put the Rega arm on the 147 to see what makes the most difference.
I’d rather like to have a mint boxed one stashed under my bed as I suspect they are undervalued at present!
Well, mine isn't mint and it's in a cupboard rather than under the bed - but they must have been severely undervalued at the time I bought it at the NVCF around ten years ago. I think I paid £60 including hinged lid. It rotates at the correct speeds, or at least did back then - it's been in the cupboard ever since. Is there a good website for refurb/servicing tips?