I agree with most youve said.

BUT Firstly the Ad I was refering to is not the black plastic wheel one it is the First Ad you put in this thread... Womens weekly dated 3rd of October...Look at the second Image..These ARE plastic wheels and plastic metal throttle control,these were not on the earlier Rotomo smile Note the groove distance and the curvature. The Tin Wheel tyre has very fine grooves and flat edges:)

The date approx for release fo the plastic wheels would have been somewhere around sept or october. The date Feb 57 would have been the winding down or end of the Rotomo 2. So from sept/oct 56 to febuary 57 would have been the last 25,000 plastic wheel rotomos.

In addition the quote for the 148,000 export mowers is for 1958 and does not include the rotomo,In addition export models did not use our serial sequence. I will try and find figures for 1956 as from memory it states that 60,000 mowers were produced in this year. ( I need to find you this reference) So from Aug 55 The start of the Model 1 in your Ad to Oct 56 will give you a Total of 75000 mowers yes? So since the model 1 had approx 8-9,000 in its run,that leaves 65,000 Tin wheel Rotomos. What needs to be found is when the Model 2 started,we have no Ad confirming this as yet. Since before the move to Milperra production was nowhere near that of 58. I would put production at approx half that,possibly making the Rotomo 2 start at the beggingng of 56. Your date of manufacture for 38952 would be as you said Im thinking between may and June smile Now what you reakon? lols.. But seriously if the first rotom 2 Ad can be found,then we can count from then to Oct 56 then to Feb 57 and get a near perfect picture