The two feed belts are listed as 2150 or Z370 and 2180 or Z445, both of which appear to be obsolete.
However, a standard belt, the 10x425 Li (serrated on the inner face for flexibility) and made by Optibelt fits the lower clutch-to feed-shaft position.
As no suitable V-belt for the upper position spindle-pulley-to clutch can be found, a suitable alternative is an 8 mm Polycord belt that can be ordered here. A length of 380 mm long to weld together is required (simple instructions are provided).
To fit the feed belts, first remove the main spindle-to-intermediate pulley (front) drive belt from the spindle pulley and also lift the main spindle pulley itself. Before removing the main spindle pulley, slacken the feed-belt tensioning roller brackets. For this job, a 3/16" A/F hex key to partially unscrew the hex socket clamp screws is required. After slackening, pull the tensioning rollers clear of the feed belts.
To lift the main spindle pulley, you first need to slacken, or remove, the hex socket grub screw that's positioned in the boss below the belt/pulley housing, see picture below.