White Riding Mower Going Slow

Hello, new member here. I have a White LT-2200 Model # 13A6606H790 SERIAL # 1A154H20132. I've had problems this season with the carburetors needing cleaned. I had that done by local repair shop & it is now running fine. However, after getting it home the V belt came loose . I returned it to the repair shop, they replaced the drive (long) belt, 2 pulleys & replaced a broken bolt in the v pulley. When I got it home I mowed my yard (about 2-1/2 acres with steady slope) & the grass was very high & thick. The v belt came off a couple of times & finally broke & shredded. I replaced with a after market (it was July 4 holiday, repair shop closed) & finished my mowing. As I finished the mower stopped & I noticed the v belt was off again & the tension springs (part # 732-0963 & 732-0384) were broke. I have since replaced the v-belt with OEM, replaced both springs per OEM. However, the mower now runs very slowly; about 1/2 the speed as normal. I noticed this seems to be a recurring theme among this era of mowers regardless of manufacturer. However; there is little information of how to fix it or for that matter exactly what is wrong. My mower runs fine, cuts grass fine, just runs very slowly whether I have cruise control engaged or not. I was hoping the springs were the issue, but i've ruled them out. Any ideas on what the problem could be?

The pulleys that were replaced, were they the variable speed pulley and the front drive pulley?

I think you will find he fixed the problem which looks like it was insufficient tension in the lower belt.
Originally there was a double posting and this is the one we did not use.
If you have a problem with your mower please start a new thread.