So im gonna swap my Tsl601 speaker with a G12T-75 that belonged to my cab before.... now the problem is when i remove the screws of my TSl speaker its like its stuck with somethinge to the amp chassis. anyone whats under there? and what to do to remove the spekar from my combo?

Fender Strat 60th Anniv HotRoded

Marshall 1980 JMP 2203
Marshall JCM900 1960A Cab
Valve Jr.

VOX v847a Modded
EHX Small Clone Modded
Maxon OD-820
MXR 1978 Flanger
Digitech Whammy
TC Polytune
Custom LPB-1 Boost
Maybe they stuck some glue in there to stop vibration...you could try melting it with a hairdryer...or if its really tuff you could use solvent like acetone but this might be damaging.
it says in your sig you have a jcm 900 cab if i were you i'd just get a speaker cable and play through that and leave the speak inside alone
get yourself a 5/8ths stack
Ibanez SAS32EXFM White
Epiphone SG G400 White
Line 6 Flextone III+
Line 6 Spider III 120 (for sale £90)