328 GTS 1st Gear Wont Always Engage?

One easy test you can do to rule the clutch operation in, or out, as the problem is:

With the car on level ground, engine off (and nothing directly in front of it) put the transmission in 1st gear, push the clutch pedal down, emergency brake off, no brake pedal, and engage the starter = if the chassis lurches forward, something in the clutch system is not OK. If it doesn't = your problem is elsewhere (which it probably is).

 

Don't know what you mean by "spinning off", and probably think that it is something else, but just thought you should eliminate the clutch operation as an easy first test that doesn't require getting greasy . Having all of the six gear selections work OK with the engine not running (after not doing anything further downstream inside the gearbox) is a sign IMO that the adjustment is OKish, or did I misread your message? -- but certainly no harm in trying readjustment.

 

There are 2 ends to the shift rod, so just to be sure to ask
has the gate metal impede the ability to shift in first at any way?

shifter position adjusted in gate start at time 04;30

 

I have a similar 1st gear issue, but it's completely random. Maybe 1 in 100 starts at a stop when 1st gear won't engage. Fortunately, 2nd gear pulls nicely from a standstill. It hasn't bothered me enough to start tearing stuff apart. I do believe my clutch needs replacing soon, as I did need to adjust my clutch pedal position, so my issue could be related to that.

 

yes, as the video say crack only one nut from turnbuckle then lengthen 2nd gear engagement throw.
They then say that only crack two nuts to change the gate to shifft rod position
They make it seem that all can be done outside transaxle

 

That is most likely the shifter adjustment. I can't remember the adjustment as this was done many years ago by a mechanic to address the infrequent intermittent issue you describe. I had thought it might have been a syncro issue at the time. I vaguely recall the idea was that if you could move the lever just a tad further left in the gate for first it would work as intended, so the shifter rod adjustments getting the lever centred in the gate discussed here would seem to apply.

My main comment point is I don't think the clutch would be the culprit here.

 

That is a classic symptom of some unwanted mechanical drag somewhere in the clutch system -- bad pilot bearing, misadjusted clutch cable (or the cable having sliced down thru a non-rolling plastic roller), warped clutch disk, etc.. Having your "clutch and flywheel was done last year by a shop" proves nothing...