[Here 2 help]

Sounds like the kick start is simply locking due to compression - if you apply constant pressure until it goes over TDC and then it kicks normally, it may only be a compression issue which can be exacerbated by raw fuel in the combustion chamber. If it sets unused and gets hard to kick, that's one thing. If it is hard to kick immediately after stalling or shutting off, that's another thing. When does it get hard to kick?

Bits of metal in the oil filter is not abnormal after new parts have been installed - new parts have to break-in and part of that process is shedding bits left behind during manufacture and from the seating process between mating parts, but keep an eye on it - the rod bearing itself is shiny white and the bearing cage or retainer is bronze - if the amount of metal bits increase, something bad is happening - if they decrease, it because the parts have seated.

 

[Here 2 help]

Yeah - I'm scratching for possibilities and you are the mechanic - I am responding to a description and you are responding the the mechanical's

 

[Here 2 help]

I'm a little lost here - there are 2 springs; one on the decompressor weight and one on the lifter arm - which one came off? And the purpose of the spring on the weight is to hold it close to the allen head bolt until engine speed causes it to move outward retracting the decompressor pin. The spring on the lifter arm holds it away from the decompressor weight to reduce or eliminate noise. Neither spring should come off unless it's damaged or assemble incorrectly.

124 psi compression is in the normal range, so compression is not as much a problem as the decompressor not working properly.

 

[Here 2 help]

The other spring is on the decompressor slipper - #8, but your problem is probably the other spring not holding the decompressor down until the engine is started.