Depends on price/condition I suppose but in the seventies, both these machines were very welcome on the market. Not that cheap but affordable and bridging the gap between obviously [but sometimes versatile] domestic recorders and professional machines that were largely out of reach.
The "mu-metal" crumbly cams were heavily featured on here at one time and some people made them up for themselves in proper metal but this was always about the 4000 series. I bought one from a Forum member just in case but my 4000DS has not failed so far. I'm not sure that a "cure" was ever achieved but I don't know that much about the 1700 series
I was never that keen on earlier Tandberg machines and the joy stick controls [despite high quality recording] but I do have a 3300X now that I use to playback archive material and I find that excellent. A sort of 4000 equivalent perhaps
Akai were great at getting the maximum out of simple basic features such as using one drive motor allied to professional but basic features like VU meters and a higher speed which meant these decks were within reach. Others may, no doubt, see it differently!
Dave W
Maybe I stand corrected-there's a Cam thread re the 1720L for a start!