[ngoma]

That is good description of the IP fuel return orifice bolt, looks like you have not made a mistake there.

Do you also have a clear section of hose on the fuel return section? To inspect for air bubbles in the return line.

Problems w/ the Bosch VE IP?

They run a good long time if they are fed well-filtered fuel and if the drive belt is not too tight.

A tight drive belt will wear out the bushing that supports the end of the drive shaft which causes an air leak at that end seal. Then fuel can leak out here and allow air in when stopped, causing hard starting, poor running, and bubbles.

A few have reported broken tab on the fuel collar, dangerous, can cause runaway condition if collar slides to WOT.

More common: misc. leaks from aging seals, and possibly from changing fuel types.

Running with clogged fuel filter can damage the vane pump, reducing internal pressures which reduces internal timing advancement resulting in poor performance. More progressive vane pump damage will send metallic debris throughout the rest of the IP and can seize the fuel metering collar to the shaft, causing the runaway condition listed above.