A George Schrade PRESTO.
Substantial rust & failed spring were just begging for a rebuild .. big smile !!!

This pic is after an initial cleaning & has the pin used for retaining the spring removed .. reference empty hole in scale.

NOTE:

I wish to acknowledge fellow member, Michael Kelley Sr. for contributing this knife for this project.
Mike, you said you wished to see the inside of one of these. Well, here we go !!! *

Some light belt sanding removed the peened & expanded heads of the rivets holding the scales on.
This is with both scales removed. Also,  the locking mechanism has been dis-assembled.
OUCH .. a broken spring. It did not arrive this way. However, a day of cleaning, a few "clicks", and, it died.

Here one can see where the frame rivets have been counterbored just enough to remove the expanded heads.
A little GENTLE force & the frame begins to come apart. The visible rust is AFTER an initial cleaning. There existed substantial rust upon arrival. If one observes the inner surface of the liners / frames .. the outline of where the spring had rusted to them is evident. No wonder it failed so quickly once the unit was cleaned enough to open the blade.
Note the pivot rivet. It's oversize, hollow, & has a std size rivet passing through it that is peened to secure the bolsters in place.
The bolster & associated pin has been removed .. leaving the hollow pivot pin clearly visible.
The 3 pins holding the backspring / bladestop in place had to be further drilled. A little rust was present & hindering the dis-assembly. This part functions as a bladestop more than a backspring ..as.. there is no contact with the blade, not in the traditional sense. 

Note: the right most pin .. above the 4 & 5/32 mark .. it wasn't exactly centered when drilled. If one clicks on the pic & expands it .. it's obvious. Prudence & patience are suggested. 

Here is the complete dis-assembled unit.
NOTE:  

The pivot pin. The bearing surface has a diameter of 0.187" (3/16), which is stepped down to 0.140" (9/64) for the portion going through the frame.

The slots milled in the tang for the sear pin to drop into when locking the blade into position. There is something less than 180 degrees of rotation between the open & closed positions. This surprised me. I've seen more than one George Schrade auto that have only a single slot milled .. presumably in a single manufacturing step .. centered on the pivot point & extending to either side equal amounts that functions for both open & closed positions. Perhaps, those were later production .. after experience streamlined the process. Perhaps, it's unique to the PRESTO design. Don't know .. this is the first PRESTO I've opened.

Pivot pins with a working diameter of 0.187" are readily available. I'll probably bore the 0.140" pivot holes in the frame to 0.187" and implement a commercially available pivot pin with threaded fasteners for the final assembly.

Late Sun evening .. 03 Nov.

Ordered 0.187"  pivots  for the project.

Two of these.

And one of these.

I source many parts from Knifekits.com . Because .........

.......... their inventory, reasonable prices, & ZERO issues.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I'll be doing this rebuild over the next couple months. I do NOT intend to restore the knife. I DO intend to restore it to full functionality. I will identify sources for all parts implemented in this rebuild. I will also gladly answer questions relative to tools & procedures used. I will date & post progress as it happens.

Which will unfortunately be ..... slowly.

D ale

*  Thanks, Mike !!