questions about Yamaha U3

[caron]

Hi,
I have got 3 questions about Yamaha U3 piano:

1. Have you ever heard about a problem in Yamaha pianos that after it becomes 
    old  (more than 30 years old) the soundboard is getting distortion,cracks and the 
    sound becomes more metallic?

2. Have you heard about people having trouble with the white teflon (looks like a 
    white cigarette- I don't know the name of that part) in the mechanism of the
    Yamaha piano?

3. Do you think if I buy a Yamaha piano in an o.k condition (1974) it is probable to   
    last me for another 20 years without having to repair anything (I usually play an
    hour every day so the  wear is small)?

Thank you for your answers,
Eyal
   

[Baadshah]

not an answer im afraid- i was about to ask a simular question so excuse me for butting in on yours!! ive seen some yamaha u series pianos at seriously affordable prices (3 to 4 thousand euros)- i think they re recent arrivals from Japan, but in europe, ive never heard about problems linked to humidity differences between japan and elsewhere. this is a highly controversial issue in USA. any comments for europe (Paris)?

ive seen a u1 - amazingly rich tone (better than a more recent U3 in same shop), firm and regular action, new hammers (i suppose this is positive, although it does suggest serious wear in the past), immaculate external condition etc.

can people suggest any other signs to check?
however, checking serial number situates it in 1970 -

should i be wary of this piano on the sole grounds it is 35 years old??