Looking for Mettler wizards

Hey, gang! A week ago I landed a very sweet deal on a pair of Mettler balances - a H35 and a H10T for free



Problem is - I have absolutely no idea how the insides of these are supposed to look, but I know that they're not in perfect shape. What I'll probably do is to use one as a lab balance and the other for parts. Is one of them better than the other? I.e. would there be any reason to choose the H10T over the H35 apart from using the one requiring the least amount of work to fix? They are both identical in capacity (160 g/0,1 mg) and seem to be almost identical on the inside.

Also, I have no idea how these work. I sent an e-mail to Mettler-Toledo asking for a user manual for the H35 and sure enough, 10 minutes later I got a reply dryly informing me that the balance in question went out of production 39 years ago. Yeah, fuck you too, I thought... I found the user manual for the H10T on a museum page (), but I haven't found any for the H35 yet - any help would be appreciated. Also, technical manuals (if available) would be helpful.


Anyways, I'll just list up the problems I've found so far:





In the H10T, one cogwheel is broken. The mechanism seems to be identical with the one in the H35, so changing it shouldn't be a problem. If anyone has a spare, I'd gladly take it off their hands as well!





In both the H35 and the H10T this bastard always jumps off (picture is from the H10T) - what's the deal with that? Am I supposed to fasten it in some way? It seems to lie perfectly still until it suddenly decides to come loose and wreak havoc after I turn the knob a few times...





On the H10T, the knob marked with "1" doesn't seem to be affecting any mechanism except for the dial when the lower left button is in the "T" position. I believe it is supposed to turn the upper array of wheels (which is connected to the broken cog), but it doesn't seem to do anything. I can't see what the problem is without disassembling the whole balance, but I'm not sure if I want to do that.





Also, on the H35, the right-hand knob used for adjusting the last two decimals won't turn the "10" decimals - i.e. it will go from 0,0000 to 0,0009, not from 0,0000 to 0,0099 as it should (this works flawlessly on the H10T). Obviously, the screen for the display is missing. It looks to be the same size as on the H10T, so if I decide to go with the H35, it could probably be changed... Although I don't see how I'm supposed to get it off the H10T.





On the H10T, it seems that there's a spring missing. Although, on the H35 there's also only one spring on the right side, and the bottom hole (where the spring would go) is covered by some piece of metal, so it is obvious there shouldn't be a second spring in that one. Is the same true for the H10T?





On the H10T, this thing (a lens??) won't let the light through! What's up with that? If it's safe to take it out I'll do that, but it looks like it's a nightmare to get out (and put back in place)... Obviously I don't get any readings on the display, since the light stops before it can get there.



Any tips would be greatly appreciated! As I have stated already, I have absolutely no idea what I'm dealing with...

Anyways, like I said, I'll be picking one of these to use as a balance and the other to scavenge for spares. Right now I'm leaning towards using the H10T for the following reasons:

• The screen is there and intact
  
• The back cover (where the lamp goes) is intact - the one on the H35 is missing and they don't seem to be interchangeable
  
• The problems I've found seem to be fixable - although it remains to see what the real problem is with the non-functional knob and the lens that won't let light through
  
• The rightmost knob seems to be fully functional and runs more smoothly than the one on the H35 - I imagine this is a much more complicated mechanism to mend than the big knobs, so repairing the H10T is more appealing
  

These are my first impressions, if anyone disagree I'll gladly consider their advice.


Some final questions:

• How much can I tamper with these babies without destroying them? Are there any finicky and sensitive mechanisms that under no circumstances should be touched/disassembled? That is, to what extent can I disassemble the balances without rendering them useless?
  
• Which parts are and are not interchangeable between these balances?
  
• How do I calibrate the balance when I'm done fixing it?
  

As a final remark I'll say that I've always wanted a proper digital analytical balance... Now I don't These old Mettler balances are so incredibly gorgeous and fascinating... The cogs, dials, the tare function, the crazy optical train, it's truly a work of art, witnesses of a time long past. If I lived during the seventies I'd probably cry from the nostalgia right now. Do yourself a favor and get one of these, they can be had on eBay for 100$ or so!

And speaking of the seventies, as a thank-you for reading through my long post I will link you to a fantastic album by one of the most prominent bands of the seventies: Yes - Going for the One. I got it on vinyl a few weeks ago and I simply can't stop listening to it. It's absolutely enchanting...


Thanks for reading! ~L-E/Erlend