I suggest running first a Perl regular expression replace all from top of the file with searching for (?:  +|\t[\t ]*| (?=_M)) and use as replace string \t for converting the file to a tab separated values file. That produces for the provided input example already a well aligned data file if the tab stop value is configured with 8.

There can be next clicked in traditional menu Column on the menu item Convert to fixed column or on ribbon tab Edit in fourth group Column / block on the down arrow right to item CSV convert and in opened popup menu on item Convert to fixed-width or in contemporary menu Edit in submenu CSV convert on menu item Convert to fixed-width for opening the Convert to Fixed Columns dialog window.

In this dialog window set the options as follows:

• Scan first line only (vs. complete file) … unchecked
• Keep delimiter with fixed columns … unchecked
• Ignore separator in quotes (')… checked
• Ignore separator in double quotes (")… checked
• Separator character (^t for tab): ^t

Press the button Scan and increase all field widths with exception of last field width by three for three spaces between the data columns. For the example the field widths would be: 15, 7, 15, 4, 6, 6
Then click on button Convert and execute perhaps additionally Trim trailing spaces.
The result for the example file is:
If that reformatting must be done from time to time or even frequently and you want to do all with the execution of an UltraEdit script, see: Converting CSV data to fixed width data? That script is the replacement for the command Convert to fixed column which is not available as scripting command. The additional Perl regular expression replace all can be added easily to this script.