300 U hydrualics still not right

continuing from post of 5-30-
All torn down cleaned and put back together on machine- All works but still screeching and fluid gets very hot in just a couple minutes. Cant touch steel high pressure line from pump in about 4 minutes. Here is what I found- 1)some paint chips and black gunk, 2) scoring on the side of the safety valve spring retainer, but it moves freely by hand, no dragging.
The Regulator valve piston has a small ding on the seat, but it is small. I have two specific questions-1) could the safety valve spring retainer be in upside down? 2) could the spring be binding up?
I really don't have a gauge that's appropriate to check pressure.
Is it time to buy a replacement regulator safety block?
thanks

Safety valve orifice screen plugged in safety regulator.Take top off valve block that is fastend by four bolts.Safety orifice is removed with screwdriver.That is part number ten in parts diagram in repair book.Most likely steel filing plugging orifice.That part is still available.

yup done that, several times, drilled out to 0.031"
how many times does it take to get system cleaned out?
anything else it could be?
thanks
d

Is your little screen still on the orifice.Did you pull main screen out of supply tank.Also you should not have drilled out orifice as it meters oil to safety valve in assy.Do you have book?I will be out the rest of the working.Will check back tonight. Scott

The safety valve is actually the relief valve. It limits max pressure. Safety valve with snap ring on it goes into small bore first, then spring cup and spring goes inside of cup. Regulator valve piston goes in with the long pin in first. It has o-ring on it. Long pin part of piston goes in first. you should be able to push piston down and feel it pushing lower ball off it's seat and it should move back up on it's own when you release it. The orfice screen drilled to .031 is correct. That is the size of new ones since 1958. If you drill it out too big the system will not go on pressure. Did you cut the end of screen off so you could clean screen and then roll it up just enough to seal. If not, crud could be inside and plug orfice. The other things that can cause your problem are , like I said before, the single to double selector. I have seen them bent out of shape inside so they are not actually positioning the spool in the proper position. When it goes on demand and stays there, that tells you more oil is flowing through the regulator port than what the orfice can supply to piston, thus piston moves up and ball closes. That is exactly what you do when you move from neutral to demand. The regulator port is blocked at the valve when in neutral. When you move lever spool uncovers regulator port and dumps more oil than the other end of that regulator port in regulator valve can supply oil through the orfice, thus, pressure is built. When set to single action, movement of lever to lowering position, the regulator port stays covered thus system does not build pressure. If the do hickey in valve that turns spool to single and double is bent or broke, hard telling what position that land on the spool is so it may be port may be uncovered all the time thus you build pressure even with lever in neutral.

It sounds like the safety valve is working just fine.

The main flow of hydraulic fluid is the problem. Something is blocking it off.

Likely culprits:
1. Blockage in a line.
2. A valve not properly centered in neutral.
3. A single/double acting selector out of position.
4. Just plain put together wrong.