HP 1725A Oscilloscope, 275Mhz

[cemelec]

About 3 years ago I bought (very cheaply) a defunct HP 1725A oscilloscope. This was never intended to be my main oscilloscope, but I have great respect for well made vintage test gear, and you don't get much better than HP of yesteryear.
In its day this would have been pretty high end, and with a 275Mhz bandwidth and other features (e.g. 50 ohm input capability) it would still be of use to me.

Anyway I got it working of sorts, the main fault is that many of the contacts in the timebase switch wafers are broken. If I recall there are 5  (maybe 4?) such boards on the TB switch. I managed to kind of repair them with phosphor bronze strip - see photo - but switching TB is still unreliable. When going, it works pretty much perfectly, voltage and timebase very accurate.

Long shot - I'm wondering if anyone else has ever fixed one of these, especially the above mentoned switches, and has any tips or advice. As for actually getting spares, I think I've more chance of winning the lottery.

Many thanks
Charles

[lowimpedance]

 Unfortunately a parts donor will be the only option for original contacts. Any HP CRO from that series will do I think.
Those hand made contacts look good, perhaps some polishing and a bit of contact grease may help with reliability.

[tggzzz]

I would look carefully at the PCB part of the switch.

My 1740 became erratic because the outer rim of that black plastic piece rubbed the circuit board and eroded the PCB track from the switch contacts to the rest of the circuit. Solution was obvious: solder a very thin piece of wire across the gap, ensuring no solder migrated onto the switch contact.

[cemelec]

Thanks, but actually the PCB boards are all in pretty good shape, in fact the whole unit is, its just those contacts.  I've even been contemplating 3D printing a replacement with easier to mount contacts, but maybe there comes a point where time is better spent elsewhere....
Charles