Help needed to repair Soldron 878d

[PSYK3D]

Hi I have a soldron 878d soldering and rework station. Its one of those knock off of knock offs with a 936 style iron and a 8 pin hot air gun.
I have been happily using it since a year without any issue. Yesterday, while working with only iron, the hot air gun suddenly started blowing air at full speed like there's no tomorrow. Everything else works fine, the iron works nicely, the hot air element is heating up without issue, but I have lost speed control of the fan, it just goes at full speed all the time. Here is what I have tried so far:
1) Classic power cycle - didn't work
2) Open up the hot air gun, nothing looks funny
3) Open up the base station, checked the pcb, nothing is burnt, __However__, I found a rebellious 67k resistor who wandered too far. I have spent hours finding where it came from but no success. I'm thinking that is the culprit. The resistor seems to be broken, not burnt nor desoldered.
I would be grateful to you guys if you could help me solve this issue. If you have a similar model with similar pcb, can you please help me find this little resister's home?
Thanks 

[RussD]

little or no service information for these
you can get pdf's of the IC's they have application schematics might help
your stray resister might have shorted something best bet is follow tracking back
surface mount devices can overheat and fall off what type of resistor is it?
the fan driver will probably be a transistor 67k could be hold down on the base junction
find the fan OP and measure inputs to that device

[iocare]

Good to see someone with soldron hot air station.
My station was also working fine from last few years but suddenly stop working recently.
My issue is similar but in my case my fan stopped working entirely. Heating element starts for sometime and just nothing happens.
For me also soldering iron works fine without issue, temperature display is fine.
I also ordered another hot air gun from soldron but its same issue.
I tried replacing TIP121 transistor used for heating element/fan in hot airgun, but still nothing worked.
Tried contacting support here in India , they responded earlier and asked me to send station but I could not send as its only station I have for smd.
Now due to COVID no one is responding there.

Any thought if know about this problem.?