I still want to know how the the Brits and others are going to compete with the Germans without US machine tools
Pb, after the isolationists win the 1940 election the US companies would lose about 80% of their orders, so they would have about 2 months to decide if they would rather open plants in Canada or close down manufacturing facilities and lay off staff. (and face bankrupcy) I think shifting production to Canada is probably what is most likely to occur. They would have to ship tools, machinery parts within the 2 month "window", after that no parts from the US, (but workers could cross the border)
According to the scenario, Roosevelt loses the Nov 1940 election to an ardent isolationist, who will re-impose the neutrality laws as soon as he (and the new congress) are sworn in in Jan 1941. Any weapons, machinery, engines or raw materials (including oil) not exported by inaugeration day are subject to embargo.
One consequence of your scenario has struck me which you may want to chew over.
If the USA isn't giving any assistance to the UK then your aeroplane, weapons and naval shipyards wouldn't have been built up during the period 1939-1941.
It was the orders from the UK and France that financed the expansion of America's military infrastructure. Your ability to arm yourselves wouldn't have been nearly as well developed, leaving the USA in a very difficult position when attacked by Japan.
The British and French orders are important to the build up of the US infrastructure. US aircraft orders were small by European standards which is understandable but advanced designs were being progressed. The production facilities were built up on the back of the European orders. Financially the US manufactures were in trouble when France fell. {Martin} and Douglas in particular were in serious danger of collapse, they had invested huge sums in the creation of the factories but with France gone, there was no money coming in to pay for them. This was a key factor in the UK's decision to take on all the French orders, even if they were aircraft such as the Martin Maryland, that we originally had no interest in.
Something to consider here, in 1940 the US made 6,028 aircraft, in 1941 19,445. Only 20% of these aircraft were ordered and used by the USA, mainly because Congress did not wish to spend large sums on defence. The USAAF (Air corps) consisted of 2,500 aircraft on Sept 1 1939, with another 2,400 in Navy service. By Dec 7 1941 there were 6,311 aircraft available, of which 3,305 were in the USAAF, and about 1,200 of the 6,311 were built during 1936 -1939 (P-35, P-36, F2A, TBD,) Even with Roosevelt pushing the expansion of the Armed forces, the Air forces only increased by 1,400. The "Isolationists" who opposed Roosevelt also opposed increased military spending, they felt that it wasn't needed by the US, as long as they stayed out of "foreign entanglements"
On Nov 5 1940 the US aircraft engine manufacturers would be faced with a cancellation of over 16,000 aircraft 20,000 engines, about 80% of their 1941 production. Do you really think that they would refuse an offer to move some of their production to Canada? Or would Kindelburger, Douglas, Martin other aircraft makers close shop flip burgers at the local Cafe? As Glider points out they have invested huge sums of money, without selling all these aircraft they face bankrupcy.
Curtiss Grumman might survive with their US orders, but what about the others? In the fall of 1940 Martin had delivered about 275 Marylands, and had orders for 550 more, plus the British purchasing commision was looking for about 2,500 more light/Medium bombers in '41-'42. At the same time they had a US order for 201 B-26's but it would not go into production until mid '41. Douglas had orders for 144 SBD "Dauntless" 63 "Bostons", but over 1,000 of the Bostons were on order from Britain.
The Engine maker Pratt Whitney already has a plant in Canada, so unless the other manufacturers (Allison, Wright) want to lose orders for 16,000 or so engines to P&W, they would be invited to manufacture north of the border too.
Remember that the "Neutrality Laws" do not forbid the IMPORT of aircraft, only the export. So if Douglas (for example) made the Bostons north of the border, they could export the smaller US order back into the US.