All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
There is no sin on you working in this job in which you neither engage in what is forbidden nor help in it.
The fact that some of your colleagues sell some equipment to parties that are not permitted to deal with, or sell them to those who would use them in a forbidden manner; this does not affect the ruling of you working in the stock and keeping record of what comes in and goes out (inventory), especially that you mentioned that most customers are those with whom it is permissible to deal with.
Whoever sells a tool to someone whom he knows that he will use it in what is forbidden, then the sin falls on him and not upon you. Allah Says (what means): {And every soul earns not [blame] except against itself, and no bearer of burdens will bear the burden of another.} [Quran 6:164]
For more benefit, please refer to Fataawa 345688, 85465 and 317782.
Allah knows best.