trying to add text at the end of a line at the fist occurrence of a variable in a file - awk

Question

I've attached the text(s) file I'm working with below:
using sed I can get a result which adds the text but it's being added to every line that contained my variable which happened to be "33" in this case. I would only like the text "SLOTS" added to the first occurrence in the file and basically stop once the first is encountered. sed adds the text "SLOTS" to every line that contains my variable in my text file there are other columns that happen to have the same value as my variable. I've searched through numerous websites to get the desired results but haven't had any luck trying awk or other sed examples. any help would be greatly appreciated.
here's my current sed line:
sed '/\b'$slot_drill'\b/s/$/SLOTS/' $slot_card > $new_slot_card
what my current sed line outputs:
d25104-1.dr -- PANEL SIZE: 18x24
Drilled Slots: Yes
Tool Tool Spindle Feed Hits Max Bits Path Time
Size Speed Rate Hits (Min)
T01 126 1.0 1.0 58 1600 0.0 182.8 1.7
T02 250 1.0 1.0 9 1600 0.0 67.5 0.7
T03 12 1.0 1.0 3965 1600 2.5 514.4 4.6
T04 31 1.0 1.0 65 1600 0.0 62.0 0.6
T05 33 1.0 1.0 569 1600 0.4 46.6 0.4 SLOTS
T06 35 1.0 1.0 33 1600 0.0 45.3 0.4 SLOTS
T07 41 1.0 1.0 97 1600 0.1 79.6 0.7
T08 42 1.0 1.0 135 1600 0.1 104.6 0.9
T09 43 1.0 1.0 33 1600 0.0 53.0 0.5 SLOTS
T10 49.2 1.0 1.0 65 1600 0.0 44.2 0.4
T11 52 1.0 1.0 17 1600 0.0 40.7 0.4
T12 63.5 1.0 1.0 33 1600 0.0 55.6 0.5 SLOTS
T13 98 1.0 1.0 25 1600 0.0 52.0 0.5
Total 5104 3.2 1348.2 12.5
output that is desired:
d25104-1.dr -- PANEL SIZE: 18x24
Drilled Slots: Yes
Tool Tool Spindle Feed Hits Max Bits Path Time
Size Speed Rate Hits (Min)
T01 126 1.0 1.0 58 1600 0.0 182.8 1.7
T02 250 1.0 1.0 9 1600 0.0 67.5 0.7
T03 12 1.0 1.0 3965 1600 2.5 514.4 4.6
T04 31 1.0 1.0 65 1600 0.0 62.0 0.6
T05 33 1.0 1.0 569 1600 0.4 46.6 0.4 SLOTS
T06 35 1.0 1.0 33 1600 0.0 45.3 0.4
T07 41 1.0 1.0 97 1600 0.1 79.6 0.7
T08 42 1.0 1.0 135 1600 0.1 104.6 0.9
T09 43 1.0 1.0 33 1600 0.0 53.0 0.5
T10 49.2 1.0 1.0 65 1600 0.0 44.2 0.4
T11 52 1.0 1.0 17 1600 0.0 40.7 0.4
T12 63.5 1.0 1.0 33 1600 0.0 55.6 0.5
T13 98 1.0 1.0 25 1600 0.0 52.0 0.5
Total 5104 3.2 1348.2 12.5
desired output

Answer 1

It is difficult to tell what you are asking. A good minimal example would probably omit the shell variables and take the line you are working with as completely independent so that other people can run it on their own systems.
However, it sounds as if you are just asking how to limit sed's s command to working only for the first line it finds that is a match. In general, I think the way is to prefix a range to the command and use 0 for the beginning of the range. For example: sed '0,/foo/ {s/foo/bar}' will replace only the first instance of foo that it finds with bar.
This is an answer to this sort of problem given at https://unix.stackexchange.com/questions/188264/want-to-substitute-only-first-occurence-with-sed

Answer 2

awk to the rescue!
on a simplified file
$ cat file
1
2
3
1
2
3
append SLOT to the first occurrence of the variable slot, let's say 3.
$ awk -v value="$slot" '$1==value && !c++{$0=$0 "SLOT"} 1' file
1
2
3SLOT
1
2
3
Looking at your example you'll need to use `$2==value``